CN107946166A - Mass spectrograph and the method that the information on sample is measured using mass spectrograph - Google Patents

Abstract

A mass spectrometer and method of measuring information about a sample using the mass spectrometer are disclosed. The mass spectrometer includes an ion source, an ion trap, an ion detector, and a gas pressure regulation system, wherein, during operation of the mass spectrometer, the gas pressure regulation system is configured to maintain between 100 mTorr and The gas pressure is between 100 Torr, and the ion detector is configured to detect ions based on the mass-to-charge ratio of the ions generated by the ion source.

Description

Mass spectrometer and method of measuring information about a sample using the mass spectrometer

This application is a division of the application dated December 31, 2012, the application number is 201280078246X, and the title of the invention is "mass spectrometer and method for measuring information about samples using a mass spectrometer (formerly known as a compact mass spectrometer)" Application.

technical field

The present disclosure relates to substance identification using mass spectrometry.

Background technique

Mass spectrometers are widely used in the detection of chemical substances. In a typical mass spectrometer, molecules or particles are excited or ionized, and these excited species often break down to form ions of lower mass or react with other species to form other characteristic ions. The ion formation patterns can be interpreted by the system operator to infer the identity of the compound.

Contents of the invention

In general, in a first aspect, the disclosure features a mass spectrometer comprising an ion source, an ion trap, an ion detector, and a gas pressure regulation system, wherein, during operation of the mass spectrometer, the gas pressure regulation system is configured between the ion source, ion trap A gas pressure between 100 mTorr and 100 Torr is maintained in at least two of the ion detectors and the ion detectors are configured to detect ions according to their mass-to-charge ratios generated by the ion source.

Embodiments of a mass spectrometer can include any one or more of the following features.

During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion trap and ion detector. During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source and ion trap. During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source and ion detector. During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source, ion trap and ion detector.

The ion source may include a glow discharge ionization source. The ion source may comprise a capacitive discharge ionization source. The ion source may include a dielectric barrier discharge ionization source.

The air pressure regulation system may include an air pump configured to control the air pressure of at least two of the ion source, ion trap, and ion detector. The mass spectrometer can include a controller configured to activate the gas pump to control the gas pressure of at least two of the ion source, ion trap, and ion detector. The air pump may include a scroll pump.

During operation, the gas pressure regulation system may be configured to maintain a gas pressure between 500 mTorr and 10 Torr in at least two of the ion source, ion trap, and ion detector. During operation, the gas pressure regulation system may be configured to maintain gas pressures in at least two of the ion source, ion trap, and ion detector that differ by less than 10 Torr. During operation, the gas pressure regulation system can be configured to maintain gas pressures in the ion source, ion trap, and ion detector that differ by less than 10 Torr. During operation, the gas pressure regulation system can be configured to maintain the same gas pressure in at least two of the ion source, ion trap, and ion detector. During operation, the gas pressure regulation system can be configured to maintain the same gas pressure in the ion source, ion trap and ion detector.

The mass spectrometer may include a gas path, wherein the ion source, ion trap, and ion detector are connected to the gas path; and a gas inlet, connected to the gas path and configured such that during operation, gas particles to be analyzed pass through the gas inlet It is introduced into the gas path, and the gas particle pressure to be analyzed in the gas path is between 100mTorr and 100Torr. The gas inlet may be configured such that during operation a gas particle mixture comprising gas particles to be analyzed and atmospheric gas particles is drawn into the gas inlet and the mixture of gas particles is not filtered to remove atmospheric gas particles before being introduced into the gas circuit.

The mass spectrometer may include a sample gas inlet connected to the gas path, and a buffer gas inlet connected to the gas path, wherein the sample gas inlet and the buffer gas inlet are configured such that during operation of the mass spectrometer: gas particles to be analyzed pass through the sample The gas inlet is introduced into the gas path; the buffer gas particles are introduced into the gas path through the buffer gas inlet; and the combined pressure of the gas particles to be analyzed and the buffer gas particles in the gas path is between 100 mTorr and 100 Torr. The buffer gas particles may include nitrogen gas molecules and/or noble gas molecules.

The ion source and ion trap can be enclosed within a housing that includes a first plurality of electrodes, and the mass spectrometer can further include a support base representing a second plurality of electrodes configured to releasably engage the first plurality of electrodes. electrodes so that the housing can be repeatedly connected and disconnected from the support base. The mass spectrometer may include an attachment mechanism configured to secure the housing to the support base when the first plurality of electrodes engages the second plurality of electrodes. The attachment mechanism may include at least one of a clamp and a cam.

The first plurality of electrodes may include a pin, and the second plurality of electrodes may include a socket configured to receive the pin.

An ion detector can be enclosed within the housing. The air pressure regulating system may include a pump, and the pump may be enclosed within the housing.

The support base may include a voltage source coupled to the second plurality of electrical contacts, and a controller connected to the voltage source, wherein the controller is also connected to the ion source and ion trap when the housing is connected to the support base. During operation, the controller can be configured to determine the air pressure of at least one of the ion source, ion trap, and ion detector, and control the air pressure by activating the air pressure regulation system.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a method comprising: maintaining a gas pressure between 100 mTorr and 100 Torr in at least two of an ion source, an ion trap, and an ion detector of a mass spectrometer, and The ion's mass-to-charge ratio detects the ion.

Embodiments of the method may include any one or more of the following features.

The method may include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion trap and ion detector. The method may include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion source and ion trap. The method may include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion source and ion detector. The method may include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion source, ion trap, and ion detector. The method can include maintaining a gas pressure between 500 mTorr and 10 Torr in at least two of the ion source, the ion trap, and the ion detector. The method may include maintaining gas pressures in at least two of the ion source, ion trap, and ion detector that differ by an amount of less than 10 Torr. The method may include maintaining gas pressures in the ion source, ion trap, and ion detector that differ by less than 10 Torr. The method can include maintaining the same gas pressure in at least two of the ion source, ion trap, and ion detector. The method can include maintaining the same gas pressure in the ion source, ion trap, and ion detector.

The method may include: introducing the gas particles to be analyzed into the gas path connecting the ion source, the ion trap and the ion detector through the gas inlet, so that the pressure of the gas particles to be analyzed in the gas path is between 100 mTorr and 100 Torr. The method may include: introducing a mixture of gas particles into a gas path connecting an ion source, an ion trap, and an ion detector through a gas inlet, wherein the mixture of gas particles includes gas particles to be analyzed and atmospheric gas particles, and the gas particles The mixture is not filtered to remove atmospheric gas particles before being introduced into the air circuit.

The method may include: introducing gas particles to be analyzed into a gas path connecting the ion source, an ion trap, and an ion detector through a sample gas inlet, and introducing buffer gas particles into the gas path through a buffer gas inlet, wherein the gas path The combined pressure of the gas particles to be analyzed and the buffer gas particles is between 100 mTorr and 100 Torr. The buffer gas particles may include nitrogen gas molecules and/or noble gas molecules.

Embodiments of the method may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer including a support base characterizing a first plurality of electrodes, and a pluggable module characterizing a second plurality of electrodes. Wherein the pluggable module is configured to releasably connect to the support base by engaging the second plurality of electrical connectors with the first plurality of electrical connectors, and the pluggable module includes an ion trap connected to the gas path.

Embodiments of a mass spectrometer may include any one or more of the following features.

A pluggable module may include an ion trap connected to a gas circuit. The second plurality of electrodes may include a pin, and the first plurality of electrodes may include a socket configured to receive the pin.

The support base includes a first attachment mechanism, and the pluggable module includes a second attachment mechanism configured to engage the first attachment structure.

The first and second attachment mechanisms may be configured such that the pluggable module can only be releasably connected to the support base in one orientation. One of the first and second attachment mechanisms may include an asymmetric extension member, and the other of the first and second attachment mechanisms may include a groove configured to receive the extension member. At least one of the first and second attachment mechanisms may include a flexible sealing member. At least one of the first and second attachment mechanisms may include at least one of a clamp and a cam.

The mass spectrometer can include a gas inlet connected to the gas circuit. The mass spectrometer may include an ion detector attached to the support base. The pluggable module may include an ion detector connected to the gas circuit. The ion detector may be positioned on the support base such that when the pluggable module is connected to the support base, the ion detector is connected to the gas path.

A mass spectrometer may include a pump attached to a support base. The pluggable module may include a pump connected to the air circuit. The pump may be positioned on the support base such that the pump is connected to the air circuit when the pluggable module is connected to the support base. The pump may include a scroll pump.

Ion sources may include glow discharge ionization sources and/or capacitive discharge ionization sources.

A mass spectrometer may include an ion detector connected to the gas path, and a controller attached to the support base and connected to the ion trap. During operation of the mass spectrometer, the controller can be configured to detect ions generated by the ion source using the detector, determine information related to the identity of the detected ions, and display the information using the output interface.

The mass spectrometer may include a pump connected to the gas line and configured to maintain the pressure of the gas particles in the range from 100 mTorr to 100 Torr. The mass spectrometer can include a controller connected to the ion trap and the pump, wherein, during operation of the mass spectrometer, the controller can be configured to determine the pressure of the gas particles in the gas path and activate the pump to maintain the pressure of the gas particles at 100mTorr to 100Torr range.

The pump can be configured to maintain the pressure of the gas particles in the range from 100 mTorr to 100 Torr.

The mass spectrometer may include an enclosure surrounding the support base and the pluggable modules, the enclosure including an opening positioned adjacent the pluggable module to allow a user of the mass spectrometer to connect and disconnect the pluggable module from the support base through the opening. The mass spectrometer may include a cover that seals the opening in the enclosure when the cover is deployed. The cover may include retractable doors. The cover may comprise a cover which is completely removable from the enclosure.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer system comprising any of the mass spectrometers disclosed herein, the mass spectrometers characterizing a first pluggable module, and one or more additional pluggable modules, wherein each The additional pluggable modules include an ion trap and a third plurality of electrodes, and each additional pluggable module is configured to releasably connect to the support base by engaging the third plurality of electrodes with the first plurality of electrodes.

Embodiments of the system may include any one or more of the following features.

At least one of the additional pluggable modules may include an ion trap substantially similar to the ion trap in the first pluggable module.

The first pluggable module may include an ion source, and at least one of the additional pluggable modules may include a different ion source than the ion source of the first pluggable module. For example, the ion source of a first pluggable module may comprise a glow discharge ionization source, and at least one of the additional pluggable modules may comprise an ionization source other than the glow discharge ionization source (e.g., an electrospray ionization source, a dielectric barrier discharge ionization source, and/or capacitive discharge ionization source).

At least one of the additional pluggable modules may include a different ion trap than the ion trap in the first pluggable module. The ion trap of the first pluggable module may have a different diameter than the ion trap of at least one of the additional pluggable modules. Alternatively or additionally, the ion trap of the first pluggable module may have a different cross-sectional shape than the ion trap of at least one of the additional pluggable modules.

The first pluggable module can include an ion detector, and each of the additional pluggable modules can include an ion detector, and the ion detector of the first pluggable module can be connected to the ion detector of at least one of the additional pluggable modules. different.

At least one surface of the first pluggable module may include a first coating, and at least one surface of at least one of the additional pluggable modules may include a second coating different from the first coating.

Embodiments of the system may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer that includes a support base, an ion source mounted to the support base, an ion trap mounted to the support base, an ion detector mounted to the support base, and The support base is electrically connected to a power source for the ion source, ion trap and ion detector, wherein the power source is configured to provide power to the ion source, ion trap and ion detector when the mass spectrometer is in operation.

Embodiments of a mass spectrometer may include any one or more of the following features.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

The mass spectrometer may include a gas pressure regulation system mounted to the support base and electrically connected through the support base to an electrical power source, wherein the power source is configured to provide power to the gas pressure regulation system when the mass spectrometer is in operation. The mass spectrometer may include a controller mounted to the support base and electrically connected through the support base to the ion source, ion trap, ion detector and gas pressure regulation system. The ion source, ion trap, and ion detector can be connected to the gas circuit, and the gas pressure regulation system can be configured to maintain the gas pressure in the gas circuit in the range from 100 mTorr to 100 Torr (e.g., at 500 mTorr during operation of the mass spectrometer). to the range of 10Torr). The air pressure regulating system may include a scroll pump.

The support base may comprise a printed circuit board.

The mass spectrometer may comprise a gas inlet connected to the gas path, wherein the gas inlet is configured such that during operation of the mass spectrometer, a mixture of gas particles is introduced into the gas path through the gas inlet, the mixture comprising gas particles to be analyzed and atmospheric gases Particles, and mixtures of gas particles are introduced into the gas path without filtering atmospheric gas particles. The gas inlet can include a valve electrically connected to the controller, and during operation of the mass spectrometer, the controller can be configured to introduce the mixture of gas particles into the gas path through the gas inlet at intervals of at least 30 seconds.

During operation of the mass spectrometer, the controller can be configured to detect ions generated by the ion source using the ion detector and to adjust a duty cycle of the ion source based on the detected ions. The controller can be configured to adjust the duty cycle of the ion source by adjusting the time interval in which the ion source generates ions. The controller may be configured to adjust the duty cycle of the ion source by adjusting at least one of a duration and a magnitude of an electrical potential applied to the ion source electrode.

During operation of the mass spectrometer, the controller can be configured to determine information related to the identity of the detected ions and display this information using the output interface.

The ion source may include a glow discharge ionization source and/or a dielectric barrier discharge ionization source.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising: an ion source, an ion trap, and a detector connected to a gas circuit; a gas inlet connected to the gas circuit and characterizing a valve; a device configured to control the gas pressure in the gas circuit a pressure regulation system; and a controller connected to the valves, ion source, ion trap, and detector, wherein, during operation of the mass spectrometer, the pressure regulation system is configured to maintain an air pressure in the gas path greater than 100 mTorr, and the controller is Configuration: (a) the valve is activated to introduce a mixture of gas particles into the gas path, wherein the mixture includes gas particles to be analyzed and atmospheric gas particles, and wherein the mixture of gas particles is introduced without filtering the atmospheric gas particles ; (b) activating the ion source to generate ions from the gas particles to be analyzed; and (c) activating the detector to detect ions based on their mass-to-charge ratios.

Embodiments of a mass spectrometer may include any one or more of the following features.

The atmospheric gas particles may include at least one of nitrogen particles and oxygen particles. The pressure regulation system can be configured to maintain the air pressure in the gas circuit at greater than 500 mTorr (eg, greater than 1 Torr). The controller can be configured to activate the valve to continuously introduce the mixture of gas particles into the gas for a period of at least 10 seconds (e.g., for a period of at least 30 seconds, for a period of at least 1 minute, for a period of at least 2 minutes). on the road.

A mass spectrometer can include: a housing enclosing an ion source and an ion trap and characterizing a first plurality of electrodes coupled to the ion source and ion trap; and a support base characterizing a second plurality of electrodes configured to engage A first plurality of electrodes, wherein the housing forms a pluggable module configured to releasably connect to the support base. A controller may be attached to the support base.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

During operation, the controller can be configured to adjust the duty cycle of the ion source based on the detected ions. For example, the controller can be configured to adjust the ion source so that the ions are within a duration of 10 seconds or longer (e.g., for a duration of 30 seconds or longer, for a duration of 1 minute or longer, for a duration of 2 minutes or longer) from the gas particles to be analyzed.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosed characterization method includes: introducing a mixture of gas particles into a gas path of a mass spectrometer, wherein the mixture includes gas particles to be analyzed and atmospheric gas particles, and wherein the mixture of gas particles is in the absence of Introduced under the condition of filtering atmospheric gas particles; maintaining the air pressure in the gas path at greater than 100mTorr; using an ion source connected to the gas path to generate ions from the gas particles to be analyzed; and using a detector connected to the gas path according to the ion The mass-to-charge ratio detects ions.

Embodiments of the method may include any one or more of the following features.

The atmospheric gas particles may include at least one of nitrogen particles and oxygen particles.

The method may include maintaining an air pressure in the gas circuit at greater than 500 mTorr (eg, greater than 1 Torr). The method may include continuously introducing the mixture of gas particles into the gas path for a period of at least 10 seconds (eg, for a period of at least 30 seconds, for a period of at least 2 minutes). The method can include adjusting the ion source such that ions are generated from the gas particles to be analyzed for a duration of 10 seconds or longer (e.g., for a duration of 30 seconds or longer, for a duration of 2 minutes or longer) .

Embodiments of the method may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer including an ion source, an ion trap, an ion detector, a pressure regulation system featuring a single mechanical pump, and a controller connected to the ion source, ion trap, and ion detector, the single The mechanical pump is configured to control the gas pressure in the ion source, ion trap, and ion detector, wherein the single mechanical pump is operated at a frequency of less than 6000 revolutions per minute to control the gas pressure, and wherein the controller is configured to activate during operation of the mass spectrometer The ion detector detects ions according to their mass-to-charge ratios generated by the ion source.

Embodiments of a mass spectrometer can include any one or more of the following features.

Single mechanical pumps may include scroll pumps. A single mechanical pump can operate at less than 4000 rpm to control air pressure.

During operation of the mass spectrometer, the single mechanical pump can maintain a gas pressure between 100 mTorr and 100 Torr in at least two of the ion source, ion trap, and ion detector. During operation of the mass spectrometer, the single mechanical pump can maintain a gas pressure between 500 mTorr and 10 Torr in at least two of the ion source, ion trap, and ion detector. A single mechanical pump can maintain a common gas pressure in at least two of the ion source, ion trap, and ion detector during operation of the mass spectrometer. A single mechanical pump can maintain a differential gas pressure of 10 mTorr or less in the ion source, ion trap, and ion detector during operation of the mass spectrometer.

A controller can be connected to the pump, and during operation of the mass spectrometer, the controller can be configured to control the frequency of the pump. During operation of the mass spectrometer, the controller is configured to detect ions generated by the ion source using the ion detector and to adjust the frequency of the pump based on the detected ions.

Ion sources may include glow discharge ionization sources, dielectric barrier discharge ionization sources, and/or capacitive discharge ionization sources.

A mass spectrometer can include: a housing enclosing an ion source and an ion trap and characterizing a first plurality of electrodes coupled to the ion source and ion trap; and a support base characterizing a second plurality of electrodes configured to engage A first plurality of electrodes, wherein the housing is a pluggable module configured to releasably connect to the support base. The casing can enclose the pump. The controller may be mounted on the support base. The support base may comprise a printed circuit board. The electronic processor can be electrically connected to the ion source and ion trap through the support base.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer is less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a method comprising: using a single mechanical pump to control the gas pressure in an ion source, ion trap, and ion detector in a mass spectrometer, and using the ion detector to detect The source generates ions, wherein controlling the gas pressure using a single mechanical pump includes operating the pump at less than 6000 revolutions per minute to control the gas pressure.

Embodiments of the method may include any one or more of the following features.

The method may include operating the pump at less than 4000 revolutions per minute to control the air pressure. The method can include maintaining a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in at least two of the ion source, ion trap, and ion detector.

The method can include maintaining a common gas pressure in at least two of the ion source, the ion trap, and the ion detector. The method can include maintaining gas pressures in the ion source, ion trap, and ion detector that differ by an amount of 10 mTorr or less.

The method can include adjusting the frequency of the pump based on the detected ions (eg, based on the abundance of the detected ions).

Embodiments of the method may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising an ion source, an ion trap, an ion detector, a user interface, and a controller coupled to the ion source, ion trap, ion detector, and user interface, wherein during operation of the mass spectrometer , the controller is configured to detect ions generated by the ion source using the ion detector, determine a chemical name associated with the detected ions, and display the chemical name on the user interface, and wherein the user interface includes a control, when the chemical is displayed When activated by the user after the name, this control causes the controller to display the spectrum of the detected ions on the user interface.

Embodiments of a mass spectrometer may include any one or more of the following features.

Displaying the spectrum of the detected ions includes displaying the abundance of the detected ions as a function of the mass-to-charge ratio of the ions. The controls may include at least one of buttons, switches, and areas of the touch screen display. During operation of the mass spectrometer, the controller can also be configured to display hazards associated with detected ions on the user interface.

The ion source may include at least one of a glow discharge ionization source, a capacitive discharge ionization source, and a dielectric barrier discharge ionization source.

During operation of the mass spectrometer, the controller may be configured such that the spectrum of detected ions is not displayed until the control is activated.

Ion detectors may include Faraday detectors.

The mass spectrometer may include a pressure regulation system configured to maintain a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in the ion trap and ion detector during operation of the mass spectrometer.

The pressure regulating system may include a scroll pump.

The mass spectrometer may include: a pluggable module representing an ion source and an ion trap and a first plurality of electrodes connected to the ion source and ion trap; and a support base representing a voltage source and a second plurality of electrodes, the second plurality of electrodes Configured to engage the first plurality of electrodes, wherein the pluggable module is configured to releasably connect to the support base.

The pluggable module may include an ion detector. Pluggable modules may include pressure regulation systems.

The mass spectrometer may include a housing enclosing the pluggable module and the support base and characterizing an opening disposed adjacent the pluggable module configured to allow insertion of the pluggable module through the opening for releasable connection to the support base.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising: an ion source, an ion trap, an ion detector, a user interface, and a controller coupled to the ion source, ion trap, ion detector, and user interface, wherein the user interface includes A control that can be activated into one of at least two states by a user of the mass spectrometer, wherein, during operation of the mass spectrometer, the controller is configured to use the ion detector to detect ions generated by the ion source, determine If the control is activated to the first state, the chemical name is displayed on the user interface; and if the control is activated to the second state, the spectrum of the detected ion is displayed on the user interface.

Embodiments of a mass spectrometer may include any one or more of the following features.

The controller may also be configured to display the chemical name on the user interface if the control is activated to the second state. Displaying the spectrum of the detected ions may include displaying the abundance of the detected ions as a function of the mass-to-charge ratio of the ions. The controls may include at least one of buttons, switches, and areas of the touch screen display.

The ion source may include at least one of a glow discharge ionization source, a capacitive discharge ionization source, and/or a dielectric barrier discharge ionization source.

The mass spectrometer may include a pressure regulation system connected to the controller, wherein the pressure regulation system is configured to maintain between 100 mTorr and 100 Torr (e.g., between 500 mTorr and 10 Torr) in the ion trap and ion detector during operation of the mass spectrometer. ) air pressure. The pressure regulating system may include a scroll pump.

The mass spectrometer may include: a pluggable module including an ion source and an ion trap, and a first plurality of electrodes connected to the ion source and the ion trap; and a support base including a voltage source and a second plurality of electrodes, the second plurality of electrodes The electrodes are configured to engage the first plurality of electrodes, wherein the pluggable module is configured to releasably connect to the support base. Pluggable modules may include ion detectors and/or pressure regulation systems.

The mass spectrometer may include a housing enclosing the pluggable module and the support base and characterizing an opening disposed adjacent the pluggable module and configured to allow insertion of the pluggable module through the opening for releasable connection to the support base.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising: an ion source, an ion trap, an ion detector, a sample inlet, and a pressure regulation system, wherein the ion source, ion trap, ion detector, sample inlet, and pressure regulation system are connected to the gas path, and wherein, during the operation of the mass spectrometer, gas particles are only introduced into the gas path through the sample inlet, the pressure regulation system is configured to maintain the gas pressure in the gas path between 100mTorr and 100Torr, and the ion detector is passed The configuration detects ions generated by an ion source of gas particles based on their mass-to-charge ratio.

Embodiments of a mass spectrometer may include any one or more of the following features.

The pressure regulation system can be configured to maintain the air pressure between 500 mTorr and 10 Torr. The pressure regulation system can be configured to maintain the air pressure above 500 mTorr.

The ion source may include at least one of a glow discharge ionization source, a capacitive discharge ionization source, and a dielectric barrier discharge ionization source.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

The pressure regulating system may include a scroll pump.

The sample inlet may be configured such that the gas particles introduced into the gas path include gas particles to be analyzed and atmospheric gas particles.

The mass spectrometer can include a valve connected to the sample inlet and a controller connected to the valve, wherein, during operation of the mass spectrometer, the controller can be configured to pass the sample inlet for a period of at least 30 seconds (e.g., a period of at least 1 minute, for a period of at least 2 minutes) to continuously introduce gas particles into the gas circuit.

The mass spectrometer can include a controller connected to the ion source, wherein, during operation of the mass spectrometer, the controller can be configured to adjust the potential applied to the ion source such that the ions are within a period of at least 30 seconds (e.g., a period of at least 1 minute) , for a period of at least 2 minutes) from the ion source for continuous generation of gas particles.

The mass spectrometer may include: a pluggable module representing an ion source and an ion trap and a first plurality of electrodes connected to the ion source and ion trap; and a support base representing a voltage source and a second plurality of electrodes, the second plurality of electrodes Configured to engage the first plurality of electrodes, wherein the pluggable module is configured to releasably connect to the support base. Pluggable modules may include pressure regulation systems.

The mass spectrometer may include a housing enclosing the pluggable module and the support base and characterizing an opening disposed adjacent the pluggable module and configured to allow insertion of the pluggable module through the opening for releasable connection to the support base.

The pressure regulating system may include a single mechanical pump, wherein the single mechanical pump is configured to operate at 6000 revolutions per minute or less to maintain the air pressure in the gas path during operation of the mass spectrometer.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the present disclosure features a method that may include: introducing a mixture of gas particles into a gas path of a mass spectrometer through a single gas inlet, wherein the mixture of gas particles includes only gas particles to be analyzed and atmospheric gas particles; The gas pressure in the gas path is maintained between 100 mTorr and 100 Torr; and the ions generated from the gas particles to be analyzed are detected according to the mass-to-charge ratio of the ions.

Embodiments of the method may include any one or more of the following features.

The method may include maintaining the gas pressure between 500 mTorr and 10 Torr. The method may include maintaining the gas pressure above 500 mTorr.

The method can include continuously introducing the mixture of gas particles into the gas path through the single gas inlet for a period of at least 30 seconds (eg, for a period of at least 1 minute, for a period of at least 2 minutes).

The method can include: adjusting a potential applied to an ion source of the mass spectrometer such that ions pass from the ion source to be analyzed within a period of at least 30 seconds (e.g., within a period of at least 1 minute, within a period of at least 2 minutes). Gas particles are generated continuously.

The method may include operating a single mechanical pump at 6000 revolutions per minute or less to maintain air pressure in the air circuit.

Embodiments of the method may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising: an ion source characterizing an exit electrode through which ions exit the ion source; an ion trap characterizing an entrance electrode disposed adjacent to the exit electrode; an ion detector; and a pressure regulator A system wherein: the outlet electrode includes one or more apertures defining a cross-sectional shape of the outlet electrode, and the inlet electrode includes one or more apertures defining a cross-sectional shape of the inlet electrode; the outlet electrode has a cross-sectional shape that substantially matches the inlet electrode the cross-sectional shape of the electrodes; and during operation of the mass spectrometer, the pressure regulation system is configured to maintain a gas pressure of at least 100 mTorr in the ion trap, and the ion detector is configured to detect ions generated by the ion source based on their mass-to-charge ratio.

Embodiments of a mass spectrometer can include any one or more of the following features.

The ion trap can include one or more ion chambers that define a cross-sectional shape of the ion trap, and the cross-sectional shape of the ion trap can substantially match the cross-sectional shape of the entrance electrode.

The one or more apertures of the outlet electrode may comprise a plurality of apertures arranged in a rectangular or square matrix. The one or more apertures of the outlet electrode may comprise a plurality of apertures arranged in a hexagonal matrix. The one or more apertures of the outlet electrode may include apertures having a rectangular cross-sectional shape. The one or more apertures of the outlet electrode may include apertures having a helical cross-sectional shape. The one or more apertures of the outlet electrode may include apertures having a serpentine cross-sectional shape. The one or more apertures of the outlet electrode may comprise 4 or more apertures (e.g., 8 or more apertures, 24 or more apertures, 100 or more apertures small hole). The one or more apertures of the outlet electrode may include a plurality of apertures arranged in a serpentine pattern.

The mass spectrometer may include a voltage source connected to the exit electrode of the ion source and the first electrode, and a controller connected to the voltage source, wherein, during operation of the mass spectrometer, the controller may be configured by applying Different potentials are used to operate the ion source in one of at least two modes, the different potentials being referenced to a common ground potential. In a first of the at least two modes, the controller may be configured to apply a potential to the first electrode and the outlet electrode such that the first electrode is at a positive potential with respect to a common ground potential, and in a second of the at least two modes In mode, the controller may be configured to apply a potential to the first electrode and the second electrode such that the first electrode is at a negative potential relative to the common ground.

The mass spectrometer may include a user interface featuring a selectable control configured such that when the control is activated while operating the mass spectrometer, the controller changes the mode of operation of the ion source.

The ion source may include a glow discharge ionization source.

The mass spectrometer can include a detector coupled to the controller, wherein, during operation of the mass spectrometer, the controller can be configured to use the ion detector to detect ions generated by the ion source and adjust the ions applied to the first electrode based on the detected ions. and the potential of the exit electrode to control the duration of continuous generation of ions by the ion source. During operation of the mass spectrometer, the ion source may generate ions in a number of ionization cycles that define the frequency of the ion source, each ionization cycle may include a first time interval during which ions are generated, and a second time interval during which ions are not generated, the first and The second time interval defines the duty cycle, and the controller can be configured to adjust the duty cycle to a value between 1% and 40% (e.g., a value between 1% and 20%, a value between 1% and 10% % between values).

During operation of the mass spectrometer, the controller may be configured to determine when the ion source should be purged based on the detected ions, adjust the duty cycle of the ion source to a value between 50% and 90%, and operate the ion source for at least 30 seconds to clean the ion source.

The pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in the ion trap.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising: an ion source, an ion trap, an ion detector, a pressure regulation system, a voltage source connected to the ion source, ion trap, ion detector and pressure regulation system, and connected to A controller for an ion source, an ion trap, an ion detector, and a voltage source, wherein, during operation of a mass spectrometer, the controller is configured to activate the ion source to generate ions from gas particles and activate the ion detector to detect ions generated by the ion source , and adjust the resolution of the mass spectrometer based on the measured ions.

Embodiments of a mass spectrometer can include any one or more of the following features.

The controller can be connected to the pressure regulation system and configured to adjust the resolution by activating the pressure regulation system to change the gas pressure of at least one of the ion source and the ion trap. The controller can be configured to increase resolution by activating the pressure regulation system to reduce the gas pressure of at least one of the ion source and the ion trap.

The controller may be configured to repeatedly apply a potential to the center electrode of the ion trap using a voltage source to eject ions from the trap, the repeated application of the potential defining a repetition rate of the potential, and the resolution adjusted by varying the repetition rate of the potential. The controller can be configured to increase resolution by increasing the repetition rate of the potentials.

The controller can be configured to adjust the resolution by changing the maximum magnitude of the potential applied by the voltage source to the center electrode of the ion trap.

The controller may be configured to apply an axial potential difference between electrodes at opposite ends of the ion trap using a voltage source, and adjust the resolution by varying the magnitude of the axial potential difference. The controller can be configured to increase resolution by increasing the magnitude of the axial potential difference.

The controller may be configured to repeatedly apply a potential difference between electrodes of the ion source using a voltage source to generate ions, the repeated application of the potential defines a repetition rate of the ion source, and the resolution is adjusted by varying the repetition rate of the ion source. The controller can be configured to synchronize the repetition rate of the ion source and the repetition rate of the potential applied to the center electrode of the ion trap.

The controller may be configured to repeatedly apply a potential difference between electrodes of the ion source using a voltage source, wherein the repeated application of the potential defines a repeat time of the ion source, and the repeat time includes a period of time for applying the potential difference between the electrodes of the ion source a first time interval, and a second time interval in which no potential difference is applied between the electrodes of the ion source; and adjusting the resolution by adjusting a duty cycle of the ion source, wherein the duty cycle corresponds to the first time interval pair repetition ratio of time. The controller can be configured to increase resolution by reducing the duty cycle of the ion source.

The mass spectrometer may include a gas path to which the ion source, ion trap, ion detector, and pressure regulation system are connected; and a buffer gas inlet connected to the gas path and characterizing a valve connected to a controller, wherein, The controller is configured to control the valve to adjust the rate of buffer gas particles introduced into the gas path through the buffer gas inlet to adjust the resolution. The controller can be configured to increase the rate at which buffer gas particles are introduced into the gas path to increase resolution.

During operation of the mass spectrometer, the controller may be configured to repeatedly activate the ion source to generate ions from gas particles, activate the ion detector to detect ions generated by the ion source, and adjust the resolution of the mass spectrometer based on the detected ions until The resolution of the mass spectrometer reaches a threshold; activates the ion detector to detect ions generated from gas particles when the resolution of the mass spectrometer is at least as great as the threshold; based on ions detected when the resolution of the mass spectrometer is at least as great as the threshold Determining information about the identity of the gas particles; and displaying the information on a user interface. The information may include the chemical name of the gas particles and/or information about hazards associated with the gas particles and/or information about the class of substances to which the gas particles correspond.

During operation of the mass spectrometer, the controller can be configured to adjust the voltage source such that a potential is applied to the center electrode of the ion trap only when the resolution reaches a threshold.

The pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in at least two of the ion source, ion trap, and ion detector during operation of the mass spectrometer.

A mass spectrometer may include: a pluggable module characterizing an ion source, an ion trap, and a detector, and a first plurality of electrodes connected to the ion source, ion trap, and detector; and a support base characterizing a second plurality of electrodes, No. The two plurality of electrodes are configured to engage the first plurality of electrodes, wherein the voltage source and controller are mounted on the support base, and wherein the pluggable module is configured to releasably connect to the support base.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a method comprising: introducing gas particles into an ion source of a mass spectrometer, generating ions from the gas particles, detecting the ions using a detector of the mass spectrometer, and adjusting the ionization of the mass spectrometer based on the detected ions. resolution.

Embodiments of the method may include any one or more of the following features.

Adjusting the resolution may include changing the gas pressure in at least one of the ion source and the ion trap. The method can include increasing resolution by reducing the gas pressure of at least one of the ion source and ion trap.

The method may include repeatedly applying a potential to a center electrode of the ion trap to eject ions from the trap, the repeated application of the potential defining a repetition frequency of the potential, and adjusting the resolution by varying the repetition frequency of the potential. The method may include increasing resolution by increasing the repetition rate of the potentials. The method may include adjusting the resolution by varying the maximum magnitude of the potential applied to the center electrode of the ion trap.

The method may include applying an axial potential difference between electrodes at opposite ends of the ion trap, and adjusting the resolution by varying the magnitude of the axial potential difference. The method may include increasing resolution by increasing the magnitude of the axial potential difference.

The method may include repeatedly applying a potential difference between electrodes of the ion source to generate ions, the repeated application of the potential defining a repetition rate of the ion source, and adjusting the resolution by varying the repetition rate of the ion source. The method may include synchronizing a repetition rate of the ion source and a repetition rate of a potential applied to a center electrode of the ion trap.

The method may include repeatedly applying a potential difference between electrodes of the ion source, wherein the repeated application of the potential defines a repeat time of the ion source, and the repeat time includes a first time interval for applying the potential difference between electrodes of the ion source , and a second time interval during which no potential difference is applied between the electrodes of the ion source; and the resolution is adjusted by adjusting a duty cycle of the ion source, wherein the duty cycle corresponds to a ratio of the first time interval to the repetition time. The method can include increasing resolution by reducing the duty cycle of the ion source.

The method can include adjusting a rate at which buffer gas particles are introduced into a gas path of the mass spectrometer to adjust resolution. The method may include increasing a rate at which buffer gas particles are introduced into the gas path to increase resolution.

The method may include repeatedly activating the ion source to generate ions from the gas particles, activating the ion detector to detect the ions generated by the ion source, and adjusting the resolution of the mass spectrometer based on the detected ions until the resolution of the mass spectrometer reaches a threshold ; activating an ion detector to detect ions generated from gas particles when the resolution of the mass spectrometer is at least as great as a threshold; determining information about the identity of the gas particles based on the ions detected when the resolution of the mass spectrometer is at least as great as a threshold ; and display the information on the user interface. The information may include the chemical name of the gas particles and/or information about hazards associated with the gas particles and/or information about the class of substances to which the gas particles correspond.

The method may include applying a potential to a center electrode of the ion trap only when the resolution reaches a threshold.

The method can include maintaining a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in at least two of the ion source, ion trap, and ion detector.

Embodiments of the method may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a mass spectrometer comprising: an ion source, an ion trap, an ion detector, an air pressure regulation system featuring a single mechanical pump, and a controller coupled to the ion source, ion trap, and ion detector, wherein , during operation of the mass spectrometer, the gas pressure regulation system is configured to maintain a gas pressure between 100 mTorr and 100 Torr in at least two of the ion source, ion trap, and ion detector, and the controller is configured to activate the ion detector to A mass-to-charge ratio is used to detect ions generated by the ion source, and wherein a single mechanical pump operates at a frequency of less than 6000 revolutions per minute to maintain air pressure.

Embodiments of a mass spectrometer can include one or more of the following features. During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion trap and ion detector. During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source and ion trap. During operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source, ion trap and ion detector.

The single mechanical pump may be a scroll pump.

During operation, the gas pressure regulation system may be configured to maintain gas pressures in at least two of the ion source, ion trap, and ion detector that differ by less than 10 Torr. During operation, the gas pressure regulation system can be configured to maintain gas pressures in the ion source, ion trap, and ion detector that differ by less than 10 Torr. During operation, the gas pressure regulation system can be configured to maintain the same gas pressure in at least two of the ion source, ion trap, and ion detector.

The mass spectrometer may include a gas path, wherein the ion source, ion trap, ion detector, and gas pressure regulation system are connected to the gas path; and a gas inlet, connected to the gas path and configured so that during operation of the mass spectrometer, the The gas particles are introduced into the gas path through the gas inlet, and the total pressure in the gas path is between 100mTorr and 100Torr. The gas inlet may be configured such that during operation of the mass spectrometer a gas particle mixture comprising gas particles to be analyzed and atmospheric gas particles is drawn into the gas inlet, wherein the mixture of gas particles is not filtered to remove atmospheric gases prior to introduction into the gas path particle.

The mass spectrometer may include a gas path, wherein the ion source, ion trap, ion detector, and gas pressure regulation system are connected to the gas path; a sample gas inlet connected to the gas path; and a buffer gas inlet connected to the gas path, wherein the sample gas The inlet and the buffer gas inlet are configured such that during operation of the mass spectrometer: gas particles to be analyzed are introduced into the gas path through the sample gas inlet, buffer gas particles are introduced into the gas path through the buffer gas inlet, and The combined pressure of the analyzed gas particles and buffer gas particles is between 100 mTorr and 100 Torr. The buffer gas particles may include at least one of nitrogen gas molecules and noble gas molecules.

A mass spectrometer may include: a pluggable module representing an ion source and an ion trap and a first plurality of electrodes connected to the ion source and ion trap; and a support base representing a second plurality of electrodes configured to Releasably engaging the first plurality of electrodes such that the pluggable module may be connected to and disconnected from the support base. The mass spectrometer may include an attachment mechanism configured to secure the pluggable module to the support base when the first plurality of electrodes engages the second plurality of electrodes. The first plurality of electrodes may include a pin, and the second plurality of electrodes may include a socket configured to receive the pin.

The pluggable module may include an ion detector, and the first plurality of electrodes may be connected to the ion detector. Pluggable modules may include mechanical pumps.

The mass spectrometer may include a voltage source, wherein the voltage source and controller are attached to the support base and connected to the second plurality of electrodes.

The support base may comprise a printed circuit board. When the pluggable module is attached to the support base, the controller can be attached to the ion source and ion trap.

A single mechanical pump can operate at less than 4000 rpm to control air pressure.

The largest dimension of the mass spectrometer may be less than 35 cm. The total mass of the mass spectrometer may be less than 4.5 kg.

Embodiments of the mass spectrometer may also include any of the other features disclosed herein, where appropriate, in any combination.

In another aspect, the disclosure features a method comprising: using a single mechanical pump operating at a frequency of less than 6000 revolutions per minute to maintain gas pressure in at least two of an ion source, an ion trap, and an ion detector of a mass spectrometer, And the ions generated by the ion source are detected according to their mass-to-charge ratio, wherein the gas pressure in at least two of the ion source, ion trap and ion detector is maintained between 100 mTorr and 100 Torr.

Embodiments of the method may include any one or more of the following features.

The gas pressure in the ion source and ion trap can be maintained between 100 mTorr and 100 Torr. The gas pressure in the ion trap and ion detector can be maintained between 100 mTorr and 100 Torr. The method may include maintaining gas pressures in at least two of the ion source, ion trap, and ion detector that differ by an amount of less than 10 Torr. The method can include maintaining the same gas pressure in the ion source, ion trap, and ion detector.

The method may include: introducing a mixture of gas particles into a gas path connecting an ion source, an ion trap, and an ion detector, wherein the mixture of gas particles includes gas particles to be analyzed and atmospheric gas particles, and the mixture of gas particles is Not filtered to remove atmospheric gas particles before being introduced into the air circuit.

The method may include operating the mechanical pump at less than 4000 revolutions per minute to control the air pressure.

Embodiments of the method may also include any of the other features disclosed herein, where appropriate, in any combination.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the subject matter embodiments, suitable methods and materials are described herein below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

The details of one or more implementations are set forth in the accompanying drawings and the detailed description below. Other features and advantages will be apparent from the detailed description, drawings, and claims.

Description of drawings

Figure 1A is a schematic diagram of a compact mass spectrometer.

Figure IB is a schematic cross-sectional view of an embodiment of a mass spectrometer.

Figure 1C is a schematic cross-sectional view of another embodiment of a mass spectrometer.

Figure ID is a schematic diagram of a mass spectrometer with components mounted to a support base.

Figure IE is a schematic diagram of a mass spectrometer with pluggable modules.

Figure IF is a schematic illustration of an attachment mechanism for attaching modules of a mass spectrometer to a support base.

2A and 2B are schematic diagrams of a glow discharge ion source.

2C-2H are schematic diagrams showing electrodes of an ion source with apertures.

Figure 2I is a graph of bias potentials applied to electrodes of an ion source.

2J is a graph of bias potentials applied to electrodes of an ion source to clean the ion source.

Figure 2K is a schematic diagram of a capacitive discharge ion source.

3A is a schematic cross-sectional view of an embodiment of an ion trap.

Figure 3B is a schematic diagram of another embodiment of an ion trap.

3C is a schematic cross-sectional view of the ion trap of FIG. 3B.

Figure 4A is a schematic diagram of a voltage source.

Figure 4B is a graph showing an unamplified modulation signal for an ion trap.

Figure 4C is a graph showing a correction signal for an ion trap.

FIG. 4D is a graph showing a reference carrier.

Figure 4E is a graph showing an amplified modulation signal for an ion trap.

FIG. 4F is a graph illustrating a resonant circuit used to amplify the signal of FIG. 4E.

5A is a perspective view of an embodiment of a Faraday cup charged particle detector.

Figure 5B is a schematic diagram of the Faraday cup detector of Figure 5A.

Figure 5C is a schematic diagram of another embodiment of a Faraday cup detector.

Figure 5D is a schematic diagram of a matrix of Faraday cup detectors.

Figure 6A is a schematic diagram characterizing the pressure regulation subsystem of a scroll pump.

Figure 6B is a schematic illustration of a scroll pump flange.

Figure 7A is a perspective view of a compact mass spectrometer.

7B and 7C are schematic cross-sectional views of embodiments of compact mass spectrometers.

FIG. 8A is a flowchart showing a series of steps for measuring mass spectral information of a sample and displaying the information.

Figure 8B is a schematic diagram of an embodiment of a compact mass spectrometer.

Figure 8C is a flowchart showing a series of steps for measuring mass spectral information and adjusting the configuration of the mass spectrometer.

The same reference numerals designate the same elements in the various drawings.

Detailed ways

IOverview

Mass spectrometers used for chemical substance identification are typically large, complex instruments that consume considerable power. Such instruments are often too bulky to be portable, and thus their application is limited to environments where they can remain largely stationary. Furthermore, conventional mass spectrometers are generally expensive and require highly trained operators to interpret the ion-patterned spectra produced by the instrument to infer the identity of the chemical being analyzed.

To achieve high sensitivity and resolution, conventional mass spectrometers typically use a variety of different components designed to operate at low gas pressures. For example, conventional ion detectors such as electron multipliers do not work efficiently at pressures above about 10 mTorr. As another example, thermionic emitters used in conventional ion sources are also optimally suited to work at pressures less than 10 mTorr, and often cannot be used even when modest oxygen concentrations are present. Furthermore, conventional mass spectrometers typically include mass analyzers with geometries specifically designed to operate only at pressures less than 10 mTorr, and specifically in the microTorr range. As a result, not only are conventional mass spectrometers configured to operate at low pressures, but they also typically cannot operate at higher gas pressures due to the components they use. Higher gas pressures can damage some parts of conventional mass spectrometers. In less obvious cases, certain components may have difficulty operating at higher pressures, or perform so poorly that the mass spectrometer can no longer collect useful mass spectral information. As a result, mass spectrometers with significantly different configurations and components need to operate at high pressures (eg, pressures greater than 100 mTorr).

To achieve low pressures, conventional mass spectrometers typically include a series of pumps to evacuate the internal volume of the mass spectrometer. For example, a conventional mass spectrometer can include a roughing pump to quickly reduce the internal pressure of the system, and a turbomolecular pump to further reduce the internal pressure to microTorr values. Turbomolecular pumps are bulky and consume considerable power. However, this is only a secondary consideration for conventional mass spectrometers; the primary consideration is the ability to achieve high resolution when measuring mass spectra. Conventional mass spectrometers typically achieve resolutions of 0.1 atomic mass units (amu) or better by using the aforementioned components that operate at low pressures.

The compact mass spectrometer disclosed herein is designed to operate with low power consumption and high efficiency compared to bulky conventional mass spectrometers. To enable low power operation, the compact mass spectrometers disclosed herein do not include turbomachinery or other power hungry vacuum pumps. Instead compact mass spectrometers usually only include a single mechanical pump operating at low frequency, which significantly reduces power consumption.

By using smaller pumps, the compact mass spectrometers disclosed herein typically operate in the pressure range of 100 mTorr to 100 Torr, which is significantly higher than the operating pressure range of conventional mass spectrometers. Conventional mass spectrometers cannot be modified to operate at these higher pressures because components used in conventional instruments (e.g., electron multipliers, thermionic emitters, and ion traps) cannot operate in the pressure ranges of the compact mass spectrometers disclosed herein run within. In addition, traditional mass spectrometers typically cannot be changed to operate at higher internal pressures because such devices typically produce very poor resolution of the measured mass spectrum when doing so. Because obtaining the highest possible resolution mass spectrum is usually what we use such devices, there is little reason to modify the device to provide worse resolution.

However, the compact mass spectrometer disclosed herein provides a different type of information to the user than conventional mass spectrometers. Specifically, the compact mass spectrometers disclosed herein typically report information such as the name of the chemical being analyzed, hazard information associated with the substance, and/or the class to which the substance belongs. The compact mass spectrometer disclosed herein can also report, for example, whether a substance is or is not a particular target substance. Typically, the recorded mass spectrum is not displayed to the user unless the user activates a control that causes the mass spectrum to be displayed. As a result, unlike conventional mass spectrometers, the compact mass spectrometers disclosed herein do not need to obtain mass spectra with the highest possible resolution. Rather, further increases in resolution are not critical performance criteria as long as the quality of the mass spectra obtained is high enough to determine the information reported to the user.

By operating at lower resolution (typically, mass spectra are obtained at resolutions between 1 amu and 10 amu), the compact mass spectrometers disclosed herein consume significantly less power than conventional mass spectrometers. For example, the compact mass spectrometers disclosed herein characterize miniature ion traps that operate efficiently at pressures from 100 mTorr to 100 Torr to separate ions of different mass-to-charge ratios while consuming far less power than conventional mass analyzers such as ion traps, because of its reduced size. For example, as the size of a cylindrical ion trap decreases, the maximum voltage applied to the trap to separate ions decreases, and the frequency of the applied voltage increases. As a result, the size of the inductor and/or resonator used in the power supply line is reduced, as are the size and power consumption requirements of other components used to generate the maximum voltage.

In addition, the compact mass spectrometers disclosed herein characterize highly efficient ion sources such as glow discharge ionization sources and/or capacitive discharge ionization sources, which further reduce power consumption. High-efficiency low-power detectors such as Faraday detectors are used in the compact mass spectrometers disclosed herein, rather than using the more power-hungry electron multipliers present in conventional mass spectrometers. Due to these low power consumption components, the compact mass spectrometer disclosed herein operates efficiently and consumes a relatively small amount of electrical power. They can be powered by standard battery-based power sources (eg, lithium-ion batteries) and are easily portable due to the handheld form factor.

Because conventional mass spectrometers provide high-resolution mass spectra directly to the user, they are generally not suitable for applications where the movement of substances is scanned by untrained personnel. In particular, for the application of on-site security scanning at transportation hubs such as airports and train stations, conventional mass spectrometers are not a practical solution. Instead, such applications would instead benefit from mass spectrometers that are compact, require relatively little operating power, and provide information that is easily interpreted by non-highly trained personnel, as described above. Compact, low-cost mass spectrometers are also useful for a variety of other applications. For example, such devices can be used in laboratories to provide rapid identification of unknown chemical compounds. Because of its low cost and small footprint, laboratories can provide workers with private mass spectrometers, reducing or eliminating the need to plan analysis time at centralized mass spectrometry facilities. Compact mass spectrometers are also available in applications such as medical diagnostic testing including in clinical settings and individual patient homes. Technicians performing such tests can easily interpret the information provided by such mass spectrometers to provide real-time feedback to others and also provide rapid updates to medical facilities, physicians and other healthcare providers.

The compact, low-power mass spectrometer featured in this disclosure provides a variety of information to the user, including the identification and/or associated background information of the chemical species scanned by the mass spectrometer, including information about the class to which the species belongs (e.g., acid, base, strong oxidizers, explosives, nitro compounds), information on hazards associated with the substance, and safety advice and/or information. The mass spectrometer operates at a higher internal gas pressure than conventional mass spectrometers. By operating at higher pressures, the size and power consumption of compact mass spectrometers is significantly reduced relative to conventional mass spectrometers. Moreover, the resolution of the mass spectrometer is sufficient to allow accurate identification and quantification of various chemical species even when the mass spectrometer operates at higher pressures.

FIG. 1A is a schematic diagram of an embodiment of a compact mass spectrometer 100 . Mass spectrometer 100 includes ion source 102 , ion trap 104 , voltage source 106 , controller 108 , detector 118 , pressure regulation subsystem 120 , and sample inlet 124 . Sample inlet 124 includes a valve 129 . Optionally, mass spectrometer 100 includes a buffer gas source 150 . The components of mass spectrometer 100 are sealed within housing 122 . Controller 108 includes electronic processor 110 , user interface 112 , storage unit 114 , display 116 , and communication interface 117 .

Controller 108 is connected to ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, voltage source 106, valve 129, and optional buffer gas source 150 via control lines 127a-127g, respectively. Control lines 127a-127g allow controller 108 (eg, electronic processor 110 in controller 108) to issue operational commands to each component to which it is connected. Such commands may include, for example, signals to activate ion source 102 , ion trap 104 , detector 118 , pressure regulation subsystem 120 , valve 129 , and buffer gas source 150 . Commands to activate various components of mass spectrometer 100 may include instructions to voltage source 106 to apply electrical potentials to component elements. For example, to activate ion source 102 , controller 108 may send instructions to voltage source 106 to apply an electrical potential to electrodes in ion source 102 . As another example, to activate ion trap 104 , controller 108 may send instructions to voltage source 106 to apply a potential to electrodes in ion trap 104 . As a further example, to activate detector 118 , controller 108 may send instructions to voltage source 106 to apply a potential to a detection element in detector 118 . Controller 108 may also send signals to activate pressure regulation subsystem 120 (e.g., via voltage source 106) to control the gas pressure in various components of mass spectrometer 100, and to signal valve 129 (e.g., via voltage source 106) To allow gas particles to enter the mass spectrometer 100 through the sample inlet 124 .

In addition, controller 108 may receive signals from each component of mass spectrometer 100 via control lines 127a-127g. For example, such signals may include information regarding operating characteristics of ion source 102 and/or ion trap 104 and/or detector 118 and/or pressure regulation subsystem 120 . Controller 108 may also receive information on ions detected by detector 118 . The information may include ion currents measured by detector 118, which relate to the abundance of ions with a particular mass-to-charge ratio. The information may also include information about the particular voltage applied to the electrodes of the ion trap 104 at the time the particular ion abundance was measured by the detector 118 . A particular applied voltage is related to a particular value of the ion's mass-to-charge ratio. By correlating the voltage information with the measured abundance information, controller 108 can determine the abundance of ions as a function of mass-to-charge ratio, and can present this information in the form of a mass spectrum using display 116 .

Voltage source 106 is connected to ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, and controller 108 via control lines 126a-e, respectively. Voltage source 106 provides potential and power to each of these components via control lines 126a-e. The voltage source 106 establishes a reference potential corresponding to electrical ground with a relative voltage of 0 volts. The potentials applied by voltage source 106 to various components of mass spectrometer 100 are referenced to this ground potential. In general, voltage source 106 is configured to apply positive and negative potentials to components of mass spectrometer 100 relative to a reference ground potential. By applying potentials of different signs to the components (eg, to the electrodes of each component), electric fields of different signs can be generated within the components, which cause ions to move in different directions. Thus, by applying suitable potentials to components of mass spectrometer 100, controller 108 (via voltage source 106) can control the movement of ions within mass spectrometer 100.

Ion source 102, ion trap 104 and detector 118 are connected such that an internal passage for gas particles and ions, gas path 128, extends between these components. Sample inlet 124 and pressure regulation subsystem 120 are also connected to gas line 128 . An optional buffer gas source 150 is also connected to gas path 128, if present. Portions of gas path 128 are shown schematically in FIG. 1A . In general, gas particles and ions move in any direction in gas path 128 , and the direction of movement can be controlled by the configuration of mass spectrometer 100 . For example, ions generated in ion source 102 may be directed from ion source 102 into ion trap 104 by applying suitable potentials to electrodes in ion source 102 and ion trap 104 .

FIG. 1B shows a schematic partial cross-sectional view of mass spectrometer 100 . As shown in FIG. 1B , output aperture 130 of ion source 102 is coupled to input aperture 132 of ion trap 104 . Furthermore, an output aperture 134 of ion trap 104 is coupled to an input aperture 136 of detector 118 . As a result, ions and gas particles may flow in any direction between ion source 102 , ion trap 104 and detector 118 . During operation of mass spectrometer 100, pressure regulation subsystem 120 is operated to reduce the gas pressure in gas line 128 to a value less than atmospheric pressure. As a result, gas particles to be analyzed enter sample inlet 124 from the environment surrounding mass spectrometer 100 (eg, the environment outside housing 122 ) and move into gas path 128 . Gas particles entering ion source 102 through gas path 128 are ionized by ion source 102 . Ions diffuse from ion source 102 into ion trap 104 where they are trapped by an electric field formed when voltage source 106 applies a suitable potential to the electrodes of ion trap 104 .

The trapped ions circulate within the ion trap 14 . To analyze circulating ions, voltage source 106, under the control of controller 108, varies the magnitude of the radio frequency trapping field applied to one or more electrodes of ion trap 104. The change in amplitude is repeated, thereby defining a frequency sweep of the ion trap 104 . On varying the magnitude of the field, ions with a particular mass-to-charge ratio fall outside the orbit and some are ejected from the ion trap 104 . The ejected ions are detected by the detector 118 and information about the detected ions is sent to the controller 108 (e.g., the ion current measured by the detector 118, and the specific voltage applied to the ion trap 104 when a specific ion current is measured ).

Although sample inlet 124 is positioned in FIGS. 1A and 1B such that gas particles enter ion trap 104 from the environment outside housing 122, more generally, sample inlet 124 may be positioned elsewhere. For example, FIG. 1C shows a schematic partial cross-sectional view of mass spectrometer 100 in which sample inlet 124 is positioned such that gas particles enter ion source 102 from the environment outside housing 122 . In addition to the configuration shown in FIG. 1C , sample inlet 124 may generally be positioned anywhere along gas path 128 provided that the location of sample inlet 124 allows gas particles to enter gas path 128 from the environment outside housing 122 .

In general, the communication interface 117 may be a wired or wireless communication interface (or both). Through communication interface 117, controller 108 can be configured to communicate with a variety of devices, including remote computers, mobile phones, and surveillance and security scanners. Communication interface 117 may be configured to send and receive data over various networks including, but not limited to, Ethernet, wireless WiFi, cellular, and Bluetooth wireless. Controller 108 can communicate with remote devices using communication interface 117 to obtain various information, including the operating and configuration settings of mass spectrometer 100, and information about substances of interest, including records of mass spectra of known substances , the hazard associated with the particulate matter, the class to which the substance of interest belongs, and/or the spectral signature of the known substance. This information can be used by controller 108 to analyze sample measurements. The controller 108 may also send information to a remote device, including an alert message for a particular substance (eg, hazardous and/or explosive) detected by the mass spectrometer 100 .

The mass spectrometers disclosed herein are both compact and capable of low power operation. To achieve compact size and low power operation, the various mass spectrometer components, including ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, and voltage source 106, are carefully designed and configured to balance space requirements and power consumption minimized. In conventional mass spectrometers, the vacuum pumps used to achieve low internal operating pressures (eg, 1×10 ⁻³ Torr or less) are large and consume a considerable amount of electrical power. For example, to achieve such pressures, conventional mass spectrometers typically employ a series of two or more pumps, including a rough pump that quickly lowers the internal system pressure from atmospheric pressure to about 0.1-10 Torr, and a rough pump that reduces the internal system pressure from 10 Torr down to the desired internal operating pressure with one or more turbomolecular pumps. Both roughing pumps and turbomolecular pumps are mechanical pumps that require a considerable amount of electrical power to operate. Rough pumps (which may include, for example, piston-based pumps) typically generate significant mechanical vibrations. Turbomolecular pumps are generally sensitive to vibrations and mechanical shocks, and can have gyroscope-like effects due to high rotational speeds. As a result, conventional mass spectrometers include power supplies sufficient to meet the power consumption requirements of vacuum pumps, as well as isolation mechanisms (eg, vibration and/or rotational isolation mechanisms) to ensure that these pumps remain operational. Conventional mass spectrometers can even require that the turbomolecular pumps not move during operation, since doing so would create mechanical vibrations that would destroy the pumps. As a result, the combination of vacuum pumps and power supplies used in conventional mass spectrometers makes conventional mass spectrometers large, bulky and difficult to move.

In contrast, the mass spectrometer systems and methods disclosed herein are compact, mobile and enable low power operation. These features are achieved in part by eliminating turbomolecular pumps, roughing pumps, and other large mechanical pumps that are common to conventional mass spectrometers. Instead of these large pumps, small, low power consumption single mechanical pumps are used to control the air pressure within the mass spectrometer system. The single mechanical pumps disclosed herein for use in mass spectrometer systems cannot reach pressures as low as conventional turbomolecular pumps. As a result, the systems disclosed herein operate at higher internal gas pressures than conventional mass spectrometers.

Operating at higher pressures generally reduces the resolution of the mass spectrometer due to various mechanisms such as collision-induced line broadening and charge exchange between molecular fragments, such as explained in detail below. As used herein, "resolution" is defined as the full width at half maximum (FWHM) at the measured mass peak. The resolution of a particular mass spectrometer is determined by measuring the FWHM of all peaks occurring in the mass-to-charge ratio range from 100 to 125 amu, and choosing as resolution the largest FWHM corresponding to a single peak (e.g., corresponding to two or more The peak widths of closely spaced sets of peaks are excluded). To determine resolution, chemicals with known mass spectra such as toluene can be used.

Although the resolution of a mass spectrometer operating at higher pressures will decrease, the mass spectrometers disclosed herein are configured such that the reduced resolution does not compromise the effectiveness of the mass spectrometer. Specifically, the mass spectrometers disclosed herein are configured such that when a chemical species of interest is scanned using the mass spectrometer, the mass spectrometer reports to the user information about the identity of the species, rather than mass-resolved spectra of molecular ions as is common in conventional mass spectrometers. . In certain embodiments, algorithms used in mass spectrometers disclosed herein can compare measured ion fragment patterns with known fragment pattern information to determine information such as the identity of the substance of interest, hazard information about the substance of interest and/or one or more compound classes to which the substance of interest belongs. In certain embodiments, the algorithm may include an expert system that determines information about the identity of the substance of interest. For example, a digital filter can be used to search for a particular feature in the measured spectrum of a substance of interest, and based on the presence or absence of that feature in the spectrum, the substance can be identified as corresponding to a particular target substance or not.

When the controller 108 performs the aforementioned analysis, the reduced resolution due to operating at higher pressures can be compensated for by the system disclosed herein. That is, the lower resolution due to high pressure operation is of no concern to users of the mass spectrometers disclosed herein, provided a reliable correspondence between measured fragmentation patterns and reference information can be performed. Thus, even though the mass spectrometers disclosed herein operate at higher pressures than conventional mass spectrometers, they are still useful in a variety of applications such as security scanning, medical diagnostics, and laboratory analysis, where the user primarily The focus is on the identification of the species of interest rather than the detailed examination of the ion fragment patterns of the species, and where the user may not have advanced training in mass spectral interpretation.

By using a single small mechanical pump, the weight, size, and power consumption of the mass spectrometers disclosed herein are greatly reduced relative to conventional mass spectrometers. Accordingly, the mass spectrometers disclosed herein generally include a pressure regulation subsystem 120, which represents a small mechanical pump configured to convert the internal air pressure (e.g., the air pressure in gas line 128, and ion source 102 connected to gas line 128 to , the gas pressure in the ion trap 104 and the detector 118) maintained between 100mTorr and 100Torr (for example, between 100mTorr and 500mTorr, between 500mTorr and 100Torr, between 500mTorr and 10Torr, between 500mTorr and 5Torr, between 100mTorr and 1Torr). In certain embodiments, the pressure regulation subsystem is configured to maintain the internal air pressure in a mass spectrometer disclosed herein above 100 mTorr (eg, above 500 mTorr, above 1 Torr, above 10 Torr, above 20 Torr).

At the aforementioned pressures, the mass spectrometers disclosed herein detect ions at a resolution of 10 amu or better. For example, in certain embodiments, the mass spectrometers disclosed herein have a resolution of 10 amu or better as measured above (e.g., 8 amu or better, 6 amu or better, 5 amu or better, 4 amu or better). better, 3amu or better, 2amu or better, 1amu or better). In general, any of these resolutions can be achieved using the mass spectrometers disclosed herein at any of the aforementioned pressures.

In addition to the pump, pressure regulation subsystem 120 may include various other components. In some embodiments, pressure regulation subsystem 120 includes one or more pressure sensors. One or more pressure sensors may be configured to measure the air pressure in a fluid conduit, such as air line 128 , to which pressure regulation subsystem 120 is connected. Measurements of air pressure may be sent to pump and/or controller 108 within pressure regulation subsystem 120 and may be displayed on display 116 . In certain embodiments, pressure regulation subsystem 120 may include other elements for fluid handling, such as one or more valves, orifices, seals, and/or fluid conduits.

To ensure efficient operation of the pressure regulation subsystem to control internal pressure in the mass spectrometers disclosed herein, the internal volume of the mass spectrometer (eg, the volume pumped through the pressure regulation subsystem) is significantly reduced relative to the internal volume of conventional mass spectrometers. The reduced internal volume adds to the benefit of reducing the overall size of the mass spectrometers disclosed herein, making them compact, portable, and capable of one-handed operation by the user.

As shown in FIGS. 1B and 1C , the internal volume of the mass spectrometer disclosed herein includes the internal volume of ion source 102 , ion trap 104 , and detector 118 and the regions between these components. More generally, the internal volume of the mass spectrometer disclosed herein corresponds to the volume of gas path 128—that is, the volume of all connected spaces within mass spectrometer 100 through which gas particles and ions can circulate. In certain embodiments, mass spectrometer 100 has an internal volume ^{of 10} cm or less (e.g., 7.0 cm or less, 5.0 cm or less, 4.0 ^cm or less, ^{3.0 cm} or less, 2.5cm ³ or smaller, 2.0cm ³ or smaller, 1.5cm ³ or smaller, 1.0cm ³ or smaller).

In certain embodiments, the mass spectrometers disclosed herein are fully integrated on a single support base. ID is a schematic diagram of an embodiment of a mass spectrometer 100 in which all components of the mass spectrometer 100 are integrated onto a single support base 140 . As shown in FIG. 1D , each of ion source 102 , ion trap 104 , detector 118 , controller 108 , and voltage source 106 are mounted on and electrically connected to support base 140 . Support base 140 is a printed circuit board and includes control wires that run between various components of mass spectrometer 100 . Thus, for example, voltage source 106 provides power to ion source 102, ion trap 104, detector 118, controller 108, and pressure regulation subsystem 120 via control lines (e.g., control lines 126a-e) integrated into support base 140 . In addition, each of ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, and voltage source 106 are connected to a controller by control lines (e.g., control lines 127a-e) integrated into support base 140 108 so that the controller 108 can send electrical signals to and thereby receive electrical signals from each of these components through the support base 140 .

Integration on a single support base such as a printed circuit board offers several important advantages. Support base 140 provides a stable platform for the components of mass spectrometer 100 , ensuring that each component is mounted stably and securely, and reducing the likelihood of damage to components during rough handling of mass spectrometer 100 . Additionally, mounting all components on a single support base simplifies the manufacturing process of mass spectrometer 100 because support base 140 provides a reproducible template for positioning and connecting the various components to one another. Furthermore, by integrating all of the control lines on the support base so that both power and control signals are routed between the components through the support base 140, the integrity of the electrical connections between the components is maintained - such connections are much more likely to be possible than through the support base 140. Individual wires extending between components form connections that are less prone to fraying and/or wire breakage.

Furthermore, by integrating the components of mass spectrometer 100 on a single support base, mass spectrometer 100 has a compact profile. Specifically, the maximum dimension of the support base 140 (for example, the maximum linear distance between any two points on the support base 140) may be 25 cm or less (for example, 20 cm or less, 15 cm or less, 10 cm or less , 8cm or less, 7cm or less, 6cm or less).

As shown in FIG. 1D , the support base 140 is mounted on the housing 122 using mounting pins 145 . In certain embodiments, mounting pins 145 are designed to isolate support base 140 (and components mounted to support base 140 ) from mechanical shock. For example, mounting pins 145 may include a shock absorbing material (eg, a flexible material such as soft rubber) to insulate support base 140 from mechanical shock. As another example, an insulating gasket or spacer formed from a shock absorbing material may be disposed between support base 140 and housing 122 to insulate support base 140 from mechanical shocks.

In certain embodiments, the mass spectrometers disclosed herein include pluggable, replaceable modules into which multiple system components are integrated. 1E is a schematic diagram of an embodiment of a mass spectrometer 100 that includes a pluggable, replaceable module 148 and a support base 140 configured to receive the module 148 . Each of ion source 102 , ion trap 104 , detector 118 and sample inlet 124 are integrated into module 148 .

Module 148 also includes a plurality of electrodes 142 extending outwardly from the module. Within module 148 , electrodes 142 are connected to each component within the module, for example, to ion source 102 , ion trap 104 and detector 118 .

Also shown in FIG. 1E is a support base 140 (eg, a printed circuit board) on which the controller 108 , voltage source 106 and pressure regulation subsystem 120 are mounted. The support base 140 includes a plurality of electrodes 144 configured to releasably engage and disengage electrodes 142 of a module 148 . In some embodiments, for example, electrode 142 is a pin and electrode 144 is a socket configured to receive electrode 142 . Alternatively, electrode 144 may be a pin, and electrode 142 may be a socket configured to receive the pin. By aligning the electrodes 142 of the module 148 with the corresponding electrodes 144 of the support base, the module 148 can be connected to the support base 140 by applying a force in the direction indicated by the arrow in FIG. 1E such that the module 148 can be releasably connected to the support base. 140 or disconnect from the support base 140. Module 148 can be disengaged from support base 140 by applying a force in the direction opposite to the arrow.

The electrodes 144 of the support base 140 may be connected to the controller 108 and the voltage source 106, as shown in FIG. 1E. When a connection is established between electrode 142 and electrode 144 , controller 108 may send and receive signals to and from each of the components integrated into module 148 , as discussed above with respect to control line 127 . Additionally, voltage source 106 may provide power to each of the components integrated within module 148 , as discussed above with respect to control line 126 .

Pressure regulation subsystem 120 mounted to support base 140 is connected to manifold 121 via conduit 123 . Manifold 121 including one or more apertures 125 is seated on support base 140 such that when module 148 is connected to support base 140 a sealed fluid connection is established between manifold 121 and module 148 . Specifically, a fluid connection (not shown in FIG. 1E ) is established between apertures 125 in manifold 121 and corresponding apertures in module 148 . Apertures in module 148 may be formed in the walls of ion source 102 , ion trap 104 and/or detector 118 . When a sealed fluid connection is established, gas particles are pumped out of the module through the manifold 121, and the pressure regulation subsystem 120 may control the air pressure within the various components of the module 148.

Other configurations of module 148 are also possible. In some embodiments, for example, detector 118 is not part of module 148 but is instead mounted to support base 140 . In such a configuration, detector 118 is positioned on support base 140 such that when module 148 is connected to support base 140 , a sealed fluid connection is established between ion trap 104 and detector 118 . Establishing a sealed fluid connection allows circulating ions within ion trap 104 to be ejected from the trap and detected using detector 118, and also allows pressure regulation subsystem 120 to maintain a reduced gas pressure (e.g., between 100 mTorr and 100 Torr) in detector 118. between).

In certain embodiments, pressure regulation subsystem 120 may be integrated into module 148 . For example, pressure regulation subsystem 120 may be attached to the underside of ion trap 104 and directly connected to gas circuit 128 within module 148 . Pressure regulation subsystem 120 is also electrically connected to electrode 142 of module 148 . When module 148 is connected to support base 140 , pressure regulation subsystem 120 may send and receive electrical signals to and from controller 108 and voltage source 106 via electrodes 142 .

The modular configuration of mass spectrometer 100 shown in FIG. 1E provides several advantages. For example, during operation of mass spectrometer 100, certain components may become contaminated with analyte carryover. For example, analyte residues can stick to the walls of ion trap 104, reducing the efficiency with which ion trap 104 can separate ions, and contaminate analytes of other species. By integrating the ion trap 104 into the module 148, if the ion trap 104 becomes contaminated, the entire module 148 can be easily and quickly replaced in the field, ensuring that the mass spectrometer 100 can be quickly returned to operation, even by untrained users. operate. Likewise, if ion source 102 or detector 118 becomes contaminated or suffers a failure, module 148 can be easily replaced by a user of mass spectrometer 100 to return mass spectrometer 100 to operation.

The modular configuration shown in FIG. 1E also ensures that mass spectrometer 100 remains compact and portable. In some embodiments, for example, the largest dimension of module 148 (e.g., the largest linear distance between any two points on module 148) is 10 cm or less (e.g., 9 cm or less, 8 cm or less, 7 cm or smaller, 6cm or smaller, 5cm or smaller, 4cm or smaller, 3cm or smaller, 2cm or smaller, 1cm or smaller).

Reduced functioning modules 148 (eg, modules contaminated by analyte particles stuck to the interior walls of ion source 102, ion trap 104, and/or detector 118) may be regenerated and returned to service. In some embodiments, to return the module 148 to normal operation, the module may be heated while it is installed in the mass spectrometer 100 . Heating may be accomplished using heating elements 127 mounted to support base 140 . As shown in FIG. 1E , heating element 127 is positioned on support base 140 such that when module 148 is attached to support base 140, heating element 127 contacts one or more of the components of module 148 (e.g., ion source 102, ion trap 104 and detector 118).

Controller 108 may be configured to activate heating element 127 by directing voltage source 106 to apply a suitable potential to heating element 127 . The initiation of heating as well as the temperature and duration of heating may be controlled by a user of mass spectrometer 100 , for example, by activating controls on display 116 and/or entering user configuration settings into memory unit 114 . In particular embodiments, controller 108 may be configured to automatically determine that regeneration of module 148 is appropriate. For example, the controller 108 can monitor the measured ionic current over a period of time, and if the ionic current is within a specified time period (e.g., 1 hour or more, 5 hours or more, 10 hours or more, 24 hours or more , 2 days or more, 5 days or more, 10 days or more) fall by more than a threshold amount (e.g., 25% or more, 50% or more, 60% or more, 70% or more) , then the controller 108 determines that regeneration of the module 148 is necessary.

Although in FIG. 1E , heating element 127 is mounted on support base 140 , other configurations are possible. In some embodiments, for example, heating element 147 is part of module 148 and may be attached such that it directly contacts some or all of the various components of module 148 (e.g., ion source 102, ion trap 104, and detector 118).

In certain embodiments, module 148 may be removed from mass spectrometer 100 for regeneration. For example, when module 148 exhibits reduced functionality (e.g., as determined by a user of mass spectrometer 100, or automatically by controller 108 using the criteria described above), module 148 may be removed from mass spectrometer 100 and heated to restore its normal operation state. Heating can be accomplished in various ways, including heating in a general purpose oven. In certain embodiments, mass spectrometer 100 may include a dedicated insertion heater that includes a slot configured to receive module 148 . When the module is inserted into the slot and the heater is activated, the module is heated to restore its function.

While ion source 102, ion trap 104, and detector 118 are generally configured to detect and identify a wide variety of chemical species, in certain embodiments these components may be specifically adapted to detect specific classes of species. In certain embodiments, ion source 102 may be specifically configured for a particular species. For example, different potentials may be applied to electrodes of ion source 102 to generate positive or negative ions from gas particles. Additionally, the magnitude of the potential applied to the electrodes of the ion source 102 can be varied to control the efficiency with which particular species are ionized. In general, different substances have different ionization affinities depending on their chemical structure. By adjusting the polarity and potential difference between the electrodes of the ion source 102, the ionization of various species can be carefully controlled.

In certain embodiments, ion trap 104 may be specifically configured for a particular species. For example, the internal dimensions (eg, internal diameter) of ion trap 104 may be selected to facilitate the trapping and detection of ions with higher mass-to-charge ratios.

In certain embodiments, the internal gas pressure within one or more of ion source 102, ion trap 104, and detector 118 can be selected to favor softer or harder ionization mechanisms, or positive or negative ion generation . Furthermore, the magnitude and polarity of the potentials applied to the various electrodes of ion source 102 and ion trap 104 can be selected to favor a particular ionization mechanism. As discussed above, different species have different ionization affinities and may ionize in one way more efficiently than others (eg, according to one mechanism). By adjusting the gas pressure and potentials applied to the various electrodes within the mass spectrometer 100, the mass spectrometer can be adapted to specifically detect a wide variety of substances and classes of substances. Additionally, by adjusting the geometry of ion trap 104 and/or the potentials applied to its electrodes, the mass window of ion trap 104 (e.g., the range of mass-to-charge ratios that can maintain ions in circulating orbits within ion trap 104) can be selected. ).

In certain embodiments, ion source 102 may include a particular type of ionizer adapted for a particular type of species. For example, any ionization source based on glow discharge ionization, electrospray mass spectrometry ionization, capacitive discharge ionization, dielectric barrier discharge ionization, and other ionizer types disclosed herein may be used in ion source 102 .

In some embodiments, detector 118 may be specifically adapted for a particular type of detection task. For example, detector 118 may be any one or more of the detectors disclosed herein. The detectors may be arranged in a particular configuration, eg, in a matrix, with multiple detection elements, such as multiple Faraday cup detectors as will be discussed subsequently, and/or in any arrangement within the detector 118 . In addition to being adapted to detect a particular species, the detector 118 may also be adapted for a particular type of ion source and ion trap. For example, the arrangement and type of detection elements within detector 118 may be selected to correspond to the arrangement of ion chambers within ion trap 104, where ion trap 104 in particular includes a plurality of ion chambers.

In particular embodiments, one or more interior surfaces of modules 148 (eg, of ion source 102 and/or ion trap 104 and/or detector 118 ) may include one or more coatings and/or surface treatments. The coating and/or surface treatment may be tailored to a particular application, including detecting a particular type of substance, operating within a particular gas pressure range, and/or operating at a particular applied potential. Examples of coatings and surface treatments that can be used to modify the module 148 for a particular substance and/or application include Teflon (more commonly, fluoropolymer coatings), anodized surfaces, nickel, chrome.

Other components of module 148 may also be adapted to detect specific substances or classes of substances. For example, sample inlet 124 may be equipped with a filter (e.g., filter 706 in FIG. Delays entry of certain materials into the mass spectrometer compared to other channels. In certain embodiments, for example, the filter may include a HEPA filter (or similar type of filter) that removes solid, micron-sized particles such as dust particles from the flow of gas particles entering the sample inlet 124 . In particular embodiments, the filter may comprise a molecular sieve type filter that removes water vapor from the flow of gas particles entering the sample inlet 124 . These two types of filters do not filter atmospheric gas particles (eg, molecular nitrogen and oxygen molecules), but instead allow atmospheric gas particles to pass through and enter the gas path 128 of the mass spectrometer 100 . Where the present disclosure refers to a filter, such as filter 706 that does not remove or filter atmospheric gas particles, it is understood that the filter allows passage of at least 95% or more of atmospheric gas particles that encounter the filter.

Accordingly, in some embodiments, mass spectrometer 100 may include multiple replaceable modules 148 . Certain modules may be identical and directly replaceable for each other (eg in case of contamination). Other modules can be configured for different modes of operation. For example, multiple replaceable modules 148 may be configured to detect different classes of substances. A user operating mass spectrometer 100 can select the appropriate module for a particular class of substance, and can insert the selected module into support base 140 before commencing analysis. To analyze a different class of substances, the user can detach the first module from the support base 140 , select a new module and insert the new module into the support base 140 . As a result, reconfiguration of the various components of mass spectrometer 100 for various applications is quick and straightforward. Modules may also be specifically configured for different types of measurements (eg, using different ionization methods, different trapping and/or ejection potentials applied to various electrodes of the ion trap 104, and/or different detection methods). In general, each of number of replaceable modules 148 may include any of the features disclosed herein. Thus, some modules may differ based on ion sources, some modules may differ based on ion traps, and some modules may differ based on detectors. A particular module may differ from one another based on more than one of these components.

In some embodiments, one or more attachment mechanisms may be used to secure the module 148 to the support base 140 . Referring to FIG. 1F , the module 148 includes a first attachment mechanism 195 that engages a second attachment mechanism 197 on the support base 140 in the form of an extension. In some embodiments, extension 195 may be seated on support base 140 with a complementary attachment mechanism incorporated on module 148 . In some embodiments, the attachment mechanism 195 can be a cam that is rotatably engaged with the attachment mechanism 197, eg, the attachment mechanism 197 includes a groove configured to receive the cam. In certain embodiments, one or more seals 193 (eg, O-rings, gaskets, and/or other seals) formed from a flexible material such as rubber and/or silicone may be positioned to seal the module 148 from the support connection between the bases 140 .

In certain embodiments, attachment mechanisms 195 and 197 may be keyed such that module 148 will only be attached to support base 140 in a single orientation. The keyed attachment mechanism has the advantage of preventing the user from installing the module 148 in an incorrect orientation.

In some embodiments, other attachment mechanisms may be used. For example, the support base 140 and/or the modules 148 may include clamping devices 199 to secure the modules 148 to the support base 140 . One or more clamping devices may be used. Additionally, clamping devices may be used in addition to other attachment mechanisms.

In the following sections, the different components of mass spectrometer 100 will be discussed in detail, and the different modes of operation of mass spectrometer 100 will also be discussed.

II ion source

In general, ion source 102 is configured to generate electrons and/or ions. Where ion source 102 generates ions directly from the gas particles to be analyzed, the ions are then transported from ion source 102 to ion trap 104 by suitable potentials applied to ion source 192 and ion trap 104 . Ions generated by ion source 102 may be positive or negative ions depending on the magnitude and polarity of the potential applied to the electrodes of ion source 102 and the chemical structure of the gas particles to be analyzed. In some embodiments, electrons and/or ions generated by ion source 102 may collide with neutral gas particles to be analyzed to generate ions from the gas particles. During operation of ion source 102, various ionization mechanisms may occur simultaneously within ion source 102, depending on the chemical structure of the gas particles to be analyzed and the operating parameters of ion source 102.

By operating at higher internal gas pressures than conventional mass spectrometers, the compact mass spectrometers disclosed herein can use a variety of ion sources. In particular, ion sources that are small and require relatively modest amounts of electrical power to operate may be used in mass spectrometer 100 . In some embodiments, for example, ion source 102 may be a glow discharge ionization (GDI) source. In certain embodiments, ion source 102 may be a capacitive discharge ion source.

Various other types of ion sources may also be used in mass spectrometer 100, depending on the amount of power required for operation and the size of the ion source. Other ion sources suitable for use in mass spectrometer 100 include, for example, dielectric barrier discharge ion sources and thermionic radiation sources. As a further example, an ion source based on electrospray ionization (ESI) may be used in mass spectrometer 100 . Such sources may include, but are not limited to, those employing desorption electrospray ionization (DESI), secondary ion electrospray ionization (SESI), extractive electrospray ionization (EESI), and paper spray ionization (PSI). As another example, a laser desorption ionization (LDI) based ion source may be used in mass spectrometer 100 . Such sources may include, but are not limited to, those employing electrospray assisted laser desorption ionization (ELDI) and matrix assisted laser desorption ionization (MALDI). Still further, ion sources based on technologies such as Atmospheric Solids Analysis Probe (ASAP), Desorption Atmospheric Pressure Chemical Ionization (DAPCI), Desorption Atmospheric Pressure Photoionization (DAPPI), and Sonic Spray Ionization (SSI) may be used in mass spectrometer 100 . Ion sources based on nanofiber arrays (eg, carbon nanofiber arrays) are also suitable for use. Additional aspects and features of the aforementioned ion sources, as well as other examples of ion sources suitable for use in mass spectrometer 100, are disclosed, for example, in the following publications, each of which is incorporated herein by reference in its entirety: Alberici et al. in Anal. Bioanal. "Ambient mass spectrometry: bringing MS into the 'real world'" published in Chem.398:265-294 (2010); Harris et al. in Anal Chem.83:4508- "Ambient Sampling/Ion Mass Spectrometry: Applications and Current Trends", published in 4538 (2011); and "AMicro Ionizer for Portable Mass Spectrometers using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays”.

GDI sources are particularly advantageous for use in mass spectrometer 100 because they are compact and well suited to operate at low power. However, glow discharge occurs only when the gas pressure is sufficient for these sources to become active. Typically, for example, GDIs are limited to operation at gas pressures of about 200 mTorr and above. At gas pressures below 200 mTorr, it is difficult to maintain a stable glow discharge. As a result, GDI is not used in conventional mass spectrometers operating at gas pressures of 1 mTorr or less. However, because the mass spectrometers disclosed herein typically operate at gas pressures between 100 mTorr and 100 Torr, a GDI source can be used.

FIG. 2A shows an example of a GDI source 200 that includes a front electrode 210 and a back electrode 220 . The two electrodes 210 and 220 together with the housing 122 form a GDI chamber 230 . In some embodiments, GDI source 200 may also include a housing that encloses the electrodes of the source. For example, in the embodiment shown in FIG. 2B , GDI chamber 230 has a separate housing 232 that encloses electrodes 210 and 220 . Housing 232 is secured or mounted to housing 122 via securing elements 250 (eg, clamps, screws, threaded fasteners, or other types of fasteners).

As shown in FIGS. 2A and 2B , the front electrode 210 has a small hole 202 through which the gas particles to be analyzed enter the GDI chamber 230 . As used herein, the term "gas particle" refers to an atom, molecule, or aggregated gas molecule that exists as a separate entity in a gaseous state. For example, if the substance to be analyzed is an organic compound, then the gas particles of the substance are gas phase single molecules of the substance.

The small hole 202 is surrounded by an insulating tube 204 . In FIGS. 2A and 2B , orifice 202 is connected to sample inlet 124 (not shown) so that due to the pressure difference between the atmosphere outside mass spectrometer 100 and GDI chamber 230, the gas particles to be analyzed are drawn into the GDI chamber. 230 in. In addition to the gas particles to be analyzed, atmospheric gas particles are also sucked into the GDI chamber 230 due to the pressure difference. As used herein, the term "atmospheric gas particles" refers to gas atoms, molecules, such as oxygen and nitrogen molecules, in the air.

In certain embodiments, additional gas particles may be introduced into GDI source 200 to help generate electrons and/or ions in the source. For example, mass spectrometer 100 may include buffer gas source 150 connected to gas line 128 as explained above with respect to FIG. 1A . Buffer gas particles from buffer gas source 150 may be introduced directly into GDI source 200 , or may be introduced into another portion of gas path 128 and diffused into GDI source 200 . The buffer gas particles may include nitrogen molecules and/or noble gas atoms (eg, He, Ne, Ar, Kr, Xe). Part of the buffer gas particles may be ionized by electrodes 210 and 220 .

Alternatively, in some embodiments, a mixture of gas particles including the gas particles to be analyzed and atmospheric gas particles is the gas particles introduced into the GDI chamber 230 . In such embodiments, only the gas particles to be analyzed may be ionized in the GDI chamber 230 . In certain embodiments, both the gas particles to be analyzed and the permitted atmospheric gas particles may be ionized in the GDI chamber 230 .

Although aperture 202 is positioned at the center of front electrode 210 in FIGS. 2A and 2B , aperture 202 may be positioned at a different location in GDI source 200 more generally. For example, aperture 202 may be disposed in a sidewall of GDI chamber 230 connected to sample inlet 124 . Furthermore, as previously described, in some embodiments, sample inlet 124 may be positioned such that the gas particles to be analyzed are drawn directly into another component of mass spectrometer 100, such as ion trap 104 or a detector. 118. When gas particles are drawn into a component other than ion source 102 , the gas particles diffuse into ion source 102 through gas path 128 . Alternatively or additionally, when the gas particles to be analyzed are drawn directly into a component such as the ion trap 104, the ion source 102 may generate ions and/or electrons that subsequently collide with the gas particles to be analyzed within the ion trap 104, thereby Ions are generated directly from gas particles in the ion trap.

Thus, depending on where the gas particles to be analyzed are introduced into mass spectrometer 100 (eg, the location of sample inlet 124), ions can be generated from gas particles at various different locations. Ion generation can occur directly in ion source 102 and the generated ions can be transported into ion trap 104 by applying suitable potentials to the electrodes of ion source 102 and ion trap 104 . Ion generation can also occur in ion trap 104 when charged particles such as ions generated by ion source 102 (eg, buffer gas ions) and electrons enter ion trap 104, colliding with gas particles to be analyzed. Ion generation can occur in multiple places simultaneously (eg, in ion source 102 and ion trap 104 ), and all generated ions are ultimately trapped within ion trap 104 . Although the discussion in this section focuses primarily on the direct generation of ions from gas particles of interest within ion source 102, the aspects and features disclosed herein are also generally applicable to the dual generation of ions from gas particles of interest in other components of mass spectrometer 100. generation.

Various spacings between electrodes 210 and 220 may be used. In general, the efficiency with which ions are generated is determined by several factors, including the potential difference between electrodes 210 and 220, the gas pressure within GDI source 200, the distance 234 between electrodes 210 and 220, and the chemical structure of the ionized gas particles . Typically, distance 234 is relatively small to ensure that GDI source 200 remains compact. In some embodiments, for example, distance 234 between electrodes 210 and 220 is 1.5 cm or less (eg, 1 cm or less, 0.75 cm or less, 0.5 cm or less, 0.25 cm or less, 0.1cm or less).

The air pressure in GDI chamber 230 is typically regulated by pressure regulation system 120 . In some embodiments, the gas pressure in GDI chamber 230 is about the same as the gas pressure in ion trap 104 and/or detector 118 . In some embodiments, the gas pressure in GDI chamber 230 is different than the gas pressure in ion trap 104 and/or detector 118 . Typically, the gas pressure in the GDI chamber 230 is 100 Torr or less (e.g., 50 Torr or less, 20 Torr or less, 10 Torr or less, 5 Torr or less, 1 Torr or less, 0.5 Torr or less) and/or 100 mTorr or more (for example, 200 mTorr or more, 300 mTorr or more, 500 mTorr or more, 1 Torr or more, 10 Torr or more, 20 Torr or more).

During operation, GDI source 200 generates a self-sustained glow discharge (or plasma) when a voltage difference is applied between front electrode 210 and back electrode 220 by voltage source 106 under the control of controller 108 . In some embodiments, the voltage difference may be 200V or higher (eg, 300V or higher, 400V or higher, 500V or higher, 600V or higher, 700V or higher, 800V or higher) to maintain glow discharge. As discussed above, detector 118 detects ions generated by GDI source 200 and the potential difference between electrodes 210 and 220 may be adjusted by controller 108 to control the rate of ions generated by GDI source 200 .

In some embodiments, GDI source 200 is mounted directly on support base 140, and electrodes 210 and 220 are directly connected to voltage source 106 through support base 140, as shown in FIG. 1D. In some embodiments, GDI source 200 forms part of module 148, and electrodes 210 and 220 are connected to electrode 142 of module 148, as shown in Figure IE. When module 148 is inserted into support base 140 , electrodes 210 and 220 are connected to voltage source 106 through electrode 144 engaging electrode 142 .

GDI source 200 may be configured to operate in different ionization modes by applying a potential of a different polarity than the ground potential established by voltage source 106 . For example, during typical operation of GDI source 200, a small fraction of gas particles are initially ionized in GDI chamber 230 due to random processes (eg, thermal impact). In certain embodiments, a potential is applied to the front electrode 210 and the back electrode 220 such that the front electrode 210 acts as a cathode and the back electrode 220 acts as an anode. In this configuration, positive ions generated in the GDI chamber 230 are driven to the front electrode 210 due to the electric field in the chamber. Anions and electrons are driven toward the rear electrode 220 . Electrons and ions can collide with other gas particles, creating larger numbers of ions. Negative ions and/or electrons exit the GDI chamber 230 through the back electrode 220 .

In certain embodiments, a suitable potential is applied to the front electrode 210 and the back electrode 220 such that the front electrode 210 acts as an anode and the back electrode 220 acts as a cathode. In this configuration, positively charged ions generated in the GDI chamber 230 exit the chamber through the back electrode 220 . Positively charged ions can collide with other gas particles, generating larger numbers of ions.

In some embodiments, user interface 112 may include controls that allow a user to select one of the ionization modes described above. Selection of an appropriate ionization mode may depend on the nature of the species to be analyzed by mass spectrometer 100 . Certain species ionize more efficiently into positive ions, and the mode of operation is selected such that the back electrode 220 acts as a cathode. Positive ions generated by operating in this mode exit the GDI source 200 through the back electrode 220 . Alternatively, certain species ionize more efficiently into negative ions, and the mode of operation is selected such that the rear electrode 220 acts as an anode. Negative ions generated by operating in this mode exit the GDI source 200 through the rear electrode 220 . In general, controller 108 is configured to monitor the ion current measured by detector 118 and select an appropriate mode of operation of the GDI source based on the ion current. Alternatively or additionally, a user of mass spectrometer 100 may select the appropriate mode of operation using controls displayed on user interface 114 or by entering appropriate configuration settings into memory unit 114 of mass spectrometer 100 .

After ions are generated and exit the GDI chamber 230 from the rear electrode 220 through either mode of operation, the ions enter the ion trap 104 through the end cap electrode 304 . In general, the back electrode 220 may include one or more small holes 240 . The number of apertures 240 and their cross-sectional shape are generally selected to create a relatively uniform spatial distribution of ions incident on the end cap electrode 304 . As ions generated in the GDI chamber 230 exit the chamber through one or more apertures 240 in the rear electrode 220, the ions are spatially separated from each other due to collisions and space charge interactions. As a result, the overall spatial distribution of ions exiting GDI source 200 is divergent. By selecting an appropriate number of apertures 240 with a particular cross-sectional shape, the spatial distribution of ions exiting GDI source 200 can be controlled such that the distribution overlaps or fills all apertures 292 formed in end cap electrode 304 . In certain embodiments, additional ion optics (eg, ion lenses) may be positioned between back electrode 220 and end cap electrode 304 to further manipulate the spatial distribution of ions erupting from GDI source 200 . However, a particular advantage of the compact ion sources disclosed herein is that a suitable ion distribution can be obtained without additional components between the rear electrode 220 and the end cap electrode 304 .

In some embodiments, the back electrode 220 includes a single hole 240 . The cross-sectional shape of aperture 240 may be circular, square, rectangular, or may correspond more generally to a regular or irregular n-sided polygon. In some embodiments, the cross-sectional shape of apertures 240 may be irregular.

In some embodiments, the rear electrode 220 includes more than one aperture 240 . In general, the rear electrode 220 can include any number of apertures (e.g., 2 or more, 4 or more, 8 or more, 16 or more, 24 or more, 48 or more more, 64 or more, 100 or more, 200 or more, 300 or more, 500 or more), the spacing between small holes can be any amount, assuming in GDI source 200 In the case where the rear electrode 220 remains sufficiently mechanically stable during use. 2C-2H illustrate various embodiments of the back electrode 220 , each having a different aperture 240 . As shown in Figures 2C-2H, the rear electrode 220 may generally be circular, rectangular, or any other shape.

FIG. 2C shows the rear electrode 220 with a circular aperture array 242 . Although 25 apertures 242 are shown in FIG. 2C , more generally any number of apertures 242 may be present. Furthermore, while apertures 242 have a circular cross-sectional shape, more generally apertures 242 having any regular or irregular cross-sectional shape may be used. Small holes with different cross-sectional shapes may also be used in a single electrode 220 . In general, the size of the opening formed by the small hole 242 may be selected as needed, and small holes 242 of different sizes may exist in the single rear electrode 220 . In general, the number and size of the pores formed in the rear electrode 220 controls the pressure drop of the gas across the electrode. Accordingly, the aperture size and number can also be selected to achieve a particular target pressure drop across the back electrode 220 during operation of the mass spectrometer 100 .

2D-2G also illustrate exemplary embodiments of back electrode 220 having openings 243, 244, 245, and 246, respectively. In FIGS. 2D-2G , openings 243 , 244 , 245 , and 246 may be formed by slits (eg, continuous openings) or a series of small holes formed in back electrode 220 and spaced apart from each other. As shown in Figures 2D-2G, openings 243, 244, 245, and 246 may be arranged to form linear arrays of openings, arrays of concentric circles, serpentine passageways, and spiral passageways. However, the embodiments shown in Figures 2D-2G are merely exemplary. More generally, a variety of arrangements of apertures with different cross-sectional shapes and sizes can be used in the back electrode 220 .

FIG. 2H shows an embodiment of a rear electrode 220 comprising a hexagonal array of apertures 247 . The hexagonal array shown in FIG. 2H and the square or rectangular array shown in FIG. 2C are examples of regular aperture arrays that may be formed in the back electrode 220 . More generally, however, various regular aperture arrays can be used in the rear electrode 220, such as, but not limited to, circular arrays and radial arrays.

As shown in FIGS. 2A and 2B , the end cap electrode 304 of the ion trap 104 may also include one or more apertures 294 . In certain embodiments, the end cap electrode 304 includes a single hole 294 having a cross-sectional shape that is circular, square, rectangular, or other n-sided polygonal shape. In certain embodiments, the pores have an irregular cross-sectional shape.

More generally, the end cap electrode 304 may include a plurality of apertures 294 . The aperture types and their placement and criteria for selecting a particular aperture type for the end cap electrode 304 are generally similar to those discussed above with respect to the rear electrode 220 . Accordingly, the foregoing discussion applies equally to forming the aperture 294 in the end cap electrode 304 .

As shown in FIGS. 2A and 2B , the rear electrode 220 is spaced apart from the end cap electrode 304 by an amount 244 . The spacing between these electrodes allows the ions erupting from the rear electrode 220 to fill the aperture 294 formed in the end cap electrode 304 as uniformly as possible spatially divergent. To further improve uniform filling of the apertures 294 , in some embodiments, the pattern of the apertures 240 formed in the rear electrode 220 may match the pattern of the apertures 294 formed in the end cap electrode 304 .

More specifically, as shown in the example in FIG. 2H , the pattern of small holes 247 formed in the rear electrode 220 defines the cross-sectional shape of the rear electrode 220 . Likewise, the pattern of small holes formed in the end cap electrode 304 defines the cross-sectional shape of the end cap electrode 304 . In some embodiments, the cross-sectional shapes of the rear electrode 220 and the end cap electrode 304 are substantially matched. As used herein, "substantially matching" means that the relative positions of the apertures formed in the rear electrode 220 are at least 70% or more the same as the relative positions of the apertures formed in the end cap electrode 304 . For each small hole, its position corresponds to the position of its center of mass.

In some embodiments, the pattern of apertures 240 formed in back electrode 220 actually matches the pattern of apertures 294 formed in end cap electrode 304, ie, there is a one-to-one correspondence between the apertures. In general, as the aperture matching degree of the rear electrode 220 and the end cap electrode 304 increases, the distance 244 between the rear electrode 220 and the end cap electrode 304 can be reduced because the ion surge from the rear electrode 220 is more uniform The small hole 294 in the end cap electrode 304 is filled. When the apertures between the electrodes are exactly or nearly exactly matched, the distance 244 can even be reduced to zero (ie, the rear electrode 220 can be positioned directly adjacent to the end cap electrode 304), making the GDI source 200 highly compact. Furthermore, as the degree of matching between the apertures increases, the number of ions entering the apertures 294 can be maximized by reducing the number of ions striking the portion of the end cap electrode 304 between the apertures. As a result, the ion collection efficiency of the ion trap 104 can be increased. Additionally, by increasing the efficiency with which ions generated by ion source 102 are collected within ion trap 104, the overall size of rear electrode 220 and end cap electrode 304 may be reduced relative to single-hole electrodes and/or electrodes with mismatched apertures. .

In certain embodiments, back electrode 220 and end cap electrode 304 may be formed as a single component, and ions formed in GDI chamber 230 may pass through this component directly into ion trap 104 . In such embodiments, the combined back electrode and end cap electrode may comprise single pores or multiple pores as described above.

Furthermore, in some embodiments, the end cap electrodes of the ion trap 104 may serve as the front electrode 210 and the back electrode 220 of the GDI source 200 . As will be discussed in detail below, ion trap 104 includes two end cap electrodes 304 and 306 disposed on opposite sides of the trap. End cap electrode 304 can serve as front electrode 210 and end cap electrode 306 can serve as back electrode 220 by applying suitable potentials to these electrodes (eg, as described above with reference to front electrode 210 and back electrode 220 ). Thus, ion trap 104 also acts as glow discharge ion source 102 in these embodiments.

Various modes of operation can be used to generate charged particles in GDI source 200 . For example, in some embodiments, a continuous mode of operation is used. 2I includes a graph 260 illustrating an embodiment of a continuous mode of operation in which a constant bias voltage 262 is applied between the front electrode 210 and the back electrode 220 of the GDI source 200 . In this mode, charged particles are continuously generated within the ion source.

In some embodiments, GDI source 200 is configured to run in pulses. 2I includes a graph 270 illustrating an embodiment of pulsed mode operation with a bias potential 272 applied between the front electrode 210 and the back electrode 220 for a duration 274 . Repeated application of the bias potential 272 defines a repetition frequency of pulsed operation, which corresponds to the reciprocal of the time interval 276 between successive pulses. In general, the duration of time interval 276 may be significantly greater (eg, about 100 times) than the duration of time 274 during which bias potential 272 is applied to the electrodes. In some embodiments, for example, duration 274 may be about 0.1 ms and time interval 276 may be about 10 ms. More generally, duration 274 may be 5 ms or less (e.g., 4 ms or less, 3 ms or less, 2 ms or less, 1 ms or less, 0.8 ms or less, 0.6 ms or less, 0.5 ms or less, 0.4ms or less, 0.3ms or less, 0.2ms or less, 0.1ms or less, 0.05ms or less, 0.03ms or less) and the time interval 276 may be 50ms or less less (eg, 40ms or less, 30ms or less, 20ms or less, 10ms or less, 5ms or less).

When a bias potential 272 is applied to the electrodes, ions are generated for the duration of time 274 . In certain embodiments, the timing of the pulsed bias potential 272 during pulsed mode operation may be synchronized with the modulation signal 412 used to generate the high voltage RF signal 482 applied to the center electrode of the ion trap 104, as subsequently will be discussed in detail. Graph 280 in FIG. 2J is a plot of modulation signal 412 used to generate RF signal 482 applied to the center electrode of ion trap 104 . Comparing graph 280 and graph 270, when pulsed bias potential 272 is applied to the electrodes of GDI source 200, modulation signal 412 is disconnected. Ions are generated in GDI source 200 during this time interval. Subsequently, the bias potential 272 is turned off, and the modulation potential 282 is turned on. During time interval 284 ions are trapped and stabilized in ion trap 104 . Subsequently, trapped ions are ejected from ion trap 104 into detector 118 during time interval 286 by increasing the magnitude of the potential applied to the center electrode of ion trap 104 .

Pulse mode operation can have several advantages. For example, the repetition frequency and duration and/or amplitude of the pulsed bias potential 272 can be adapted to the amount of gas particles present to be analyzed and the gas pressure in the ion trap 104 . In general, controller 108 monitors the ion current measured by detector 118, and based on the magnitude of the ion current, controller 108 may adjust one or more parameters associated with pulsed mode operation.

In some embodiments, for example, the controller 108 may adjust the magnitude of the bias potential 272 . Increasing the bias potential can increase the rate at which ions are generated in GDI source 200 .

In some embodiments, the controller 108 may adjust the repetition frequency of the bias potential 272 . For certain analytes of interest, increasing the repetition rate can increase the rate at which ions are generated in GDI source 200 . For other analytes, reducing the repetition rate can increase the rate at which ions are generated in GDI source 200 . The controller 108 can be configured to adjust the repetition frequency in an adaptive manner until the rate at which ions are generated in the GDI source 200 reaches a suitable value.

In some embodiments, controller 108 may be configured to adjust the duty cycle of GDI source 200 . Referring to graph 270 , the duty cycle of GDI source 200 refers to the ratio of the duration of time 274 during which bias potential 272 is applied to the total time interval 276 . Controller 108 may be configured to adjust the duty cycle of GDI source 200 . For example, the duty cycle may be reduced to reduce the rate at which ions are generated in GDI source 200 . By reducing the rate at which ions are produced, the signal-to-noise ratio of the measured ion signal can be improved and unwanted artifacts (e.g., due to unwanted peaks produced by the GDI source 200 when measuring ions with the source 200 disconnected) can be eliminated. peak of charged particles). Alternatively, the duty cycle can be increased to increase the rate at which ions are generated in the GDI source 200 .

In some embodiments, controller 108 may be configured to adjust the value of the duty cycle between 1% and 50% (e.g., between 1% and 40%, between 1% and 30%, at between 1% and 20%, between 1% and 10%).

Another important advantage of pulsed mode operation is that the bias potential applied between electrodes 210 and 220 can be disconnected when not needed, for example when source 200 has generated ions. During most of the duty cycle of source 200, disconnecting the bias potential can result in a significant reduction in the power required to run the mass spectrometer.

Additionally, pulsed mode operation avoids the use of a door or shield disposed between the GDI source 200 and the detector 118 . Eliminating the doors and shrouds commonly used in conventional mass spectrometers can save considerable space and further reduce the amount of power required to operate mass spectrometer 100 .

In some embodiments, the operating condition of GDI source 200 can be checked using an automated calibration process. For example, a user may activate a calibration process in which one or more known reference samples are analyzed in succession. Detection of spurious peaks (ie, peaks that should not be present in the measured spectrum) may indicate contamination of the GDI source 200 . For example, either of electrodes 210 and 220 may be embedded with sticky particles or debris that may produce false peak detection. During some calibrations, no sample was injected and spurious peaks were detected against the background of mass spectrometer noise. The determination of whether GDI source 200 needs to be replaced may be based on calibration results, for example based on the number and magnitude of detected artifact peaks.

For ease of replacement, in some embodiments, ion source 102 may be configured as a separate module from other components of mass spectrometer 100 . For example, as shown in FIG. 2B , GDI source 200 may be implemented as a separate module that is easily detached from other components of mass spectrometer 100 or from housing 122 by releasing securing element 250 . Alternatively, electrodes 210 and 220 may be configured to be independently removable from GDI chamber 230 . Removal of the electrodes 210 and 220 can be achieved by, for example, removing a cover integrated into the housing 122 adjacent to the location of the electrodes. When the cover is removed from the housing 122 , the exposed electrodes can be removed from the GDI chamber 230 .

In some embodiments, GDI source 200 may be cleaned rather than replaced. For example, GDI source 200 may be cleaned by applying a bias potential to electrodes 210 and 220 corresponding to an inverse duty cycle. 2J shows a graph 263 of an inverse duty cycle, where a bias potential 264 that is inverse relative to the pulsed mode bias potential shown in graph 270 is applied to electrodes 210 and 220 during the cleaning process. Most duty cycles apply a constant DC potential, interrupted only by brief potential drops of duration 274 . These potential drops are repeated at time intervals 276 . Without wishing to be bound by theory, it is believed that the rapid voltage change facilitates removal of sticky particles embedded in electrodes 210 and 220 . Once it is determined that the GDI source 200 is cleaned (eg, using the calibration process described above), the GDI source 200 may switch to normal operation for generating ions (eg, pulsed mode operation).

In some embodiments, controller 108 may be configured to adjust the value of the duty cycle during purge to be between 50% and 100% (e.g., between 50% and 90%, between 50% and 80%) between 50% and 70%, between 50% and 60%). The inverse duty cycle can be applied for a total time of 5s or longer (e.g., 10s or longer, 20s or longer, 30s or longer, 40s or longer, 50s or longer, 1 minute or longer, 2 minutes or longer, 3 minutes or longer, 5 minutes or longer).

Other methods can also be used to clean the electrodes of the GDI source 200 if they become contaminated. In some embodiments, cleaning gas may be injected into GDI chamber 230 to facilitate cleaning sticky particles on electrodes 210 and 220 . Suitable purge gases may include, for example, inert gases. Additionally, electrode cleaning of GDI source 200 may also be facilitated by heating electrodes 210 and 220 in some embodiments. In some embodiments, electrodes 210 and 220 can be removed from GDI chamber 230 and cleaned in a suitable cleaning solution.

The foregoing discussion revolves around the measurement of false peaks to determine if the GDI source 200 is contaminated. More generally, other methods may be used in addition to or as an alternative to false peak detection. For example, controller 108 may be configured to monitor detector 118 measurements of ion current. If the ion signal measured by detector 118 flickers or changes suddenly (e.g., jumps or drops) by more than a threshold amount, or if the average detected ion/electron signal has decayed below a certain threshold, then controller 108 can automatically determine that GDI source 200 Cleaning or replacement is desired.

Various materials may be used to form electrodes in ion source 102 , including electrodes 210 and 220 in GDI source 200 . In some embodiments, the electrodes of ion source 102 may be fabricated from materials such as copper, aluminum, silver, nickel, gold, and/or stainless steel. In general, materials that do not readily absorb sticky particles are advantageous, and electrodes formed from such materials typically require less frequent cleaning or replacement.

The foregoing discussion revolved around the use of GDI source 200 in mass spectrometer 100 . However, the features, design criteria, algorithms, and aspects described above are equally applicable to other types of ion sources that may be used in mass spectrometer 100, such as capacitive discharge sources and thermionic radiation sources. In particular, capacitive discharge sources are well suited to the relatively high pressures at which mass spectrometer 100 operates. Therefore, the previous description also applies to such sources. For example, FIG. 2K shows an example of a capacitive discharge source 265 including an array of ionization sources 266 . The inset in FIG. 2K shows a single ionization source 266 with wire 267 and insulator coated wire 268 . A plasma discharge occurs from each of sources 266 when a bias potential is applied by voltage source 106 to leads 267 . Ions generated by capacitive discharge source 265 enter ion trap 104 where they are trapped and selectively ejected for detection. Additional aspects and features of capacitive discharge sources are disclosed, for example, in US Patent No. 7,274,015, which is incorporated herein by reference in its entirety.

Due to the use of compact, closely spaced electrodes, the overall size of ion source 102 can be small. The maximum dimension of ion source 102 refers to the maximum linear distance between any two points on the ion source. In certain embodiments, for example, the largest dimension of ion source 102 is 8.0 cm or less (e.g., 6.0 cm or less, 5.0 cm or less, 4.0 cm or less, 3.0 cm or less, 2.0 cm or smaller, 1.0cm or smaller).

III ion trap

As described in Section I above, ions generated by ion source 102 are trapped within ion trap 104 and circulate under the influence of an electric field formed by applying a potential to the electrodes of ion trap 104 . The voltage source 106 applies a potential to the electrodes of the ion trap 104 upon receipt of a control signal from the controller 108 . To eject circulating ions from ion trap 104 for detection, controller 108 transmits a control signal to voltage source 106 , which causes voltage source 106 to modulate the magnitude of a radio frequency (RF) field within ion trap 104 . Modulation of the amplitude of the RF field causes circulating ions within the ion trap 104 to shed their orbits and exit the ion trap 104 into the detector 118 where they are detected.

As explained in Section I above, to ensure that mass spectrometer 100 is compact and consumes a relatively small amount of electrical power during operation, mass spectrometer 100 uses only a single small mechanical pump in pressure regulation subsystem 120 to regulate its internal air pressure. As a result, mass spectrometer 100 operates at a higher internal pressure than in conventional mass spectrometers. To ensure that the gas particles drawn into the mass spectrometer 100 are rapidly ionized and analyzed, the internal volume of the mass spectrometer 100 is much smaller than that of conventional mass spectrometers. By reducing the internal volume of mass spectrometer 100 , pressure regulation subsystem 120 is able to quickly draw gas particles into mass spectrometer 100 . Furthermore, by ensuring fast ionization and analysis, a user of mass spectrometer 100 can quickly obtain information about a particular substance. The smaller internal volume of mass spectrometer 100 has the added benefit of smaller internal surface area that is prone to contamination during operation. Conventional mass spectrometers use a variety of different mass analyzers, many of which have large internal volumes maintained at low pressures during operation, and/or consume significant power during operation. For example, some mass spectrometers use linear quadrupole mass filters with large internal volumes due to their axial extension, which allow for mass filtering and large charge storage capacities. Some conventional mass spectrometers use magnetic sector mass filters, which are also generally large and consume a lot of power to generate the mass-filtering magnetic field. Conventional mass spectrometers can also use hyperbolic ion traps, which have large internal volumes and can also be difficult to manufacture.

In contrast to the aforementioned conventional ion trap technology, the mass spectrometer disclosed herein uses a compact, cylindrical ion trap for trapping and analyzing ions. FIG. 3A is a schematic cross-sectional view of an embodiment of an ion trap 104 . The ion trap 304 includes a cylindrical center electrode 302 , two end cap electrodes 304 and 306 , and two insulating spacers 308 and 310 . Electrodes 302, 304 and 306 are connected to voltage source 106 via control lines 312/314 and 316, respectively. The voltage source 106 is connected to the controller 108 via a control line 127e, and the controller 108 sends a signal to the voltage source 106 via the control line 127e, commanding the voltage source 106 to apply a potential to the electrodes of the ion trap 104.

During operation, ions generated by ion source 102 enter ion trap 104 through aperture 320 in electrode 304 . Voltage source 106 applies a potential to electrodes 304 and 306 to create an axial field (eg, symmetrical about axis 318 ) within ion trap 104 . The axial field confines the ions axially between electrodes 304 and 306 , ensuring that the ions do not exit the ion trap through aperture 320 in electrode 306 or through aperture 322 . Voltage source 106 also applies a potential to central electrode 302 to generate a radial confinement field within ion trap 104 . The radial field confines the ions radially within the inner aperture of the electrode 302 .

Both axial and radial fields exist within the ion trap 104 within which ions circulate. The orbital geometry of each ion is determined by several factors, including the geometry of the electrodes 302, 304, and 306, the magnitude and sign of the potentials applied to the electrodes, and the ion's mass-to-charge ratio. By varying the magnitude of the potential applied to the central electrode 302 , ions of a particular mass-to-charge ratio will fall out of their orbits within the trap 104 and exit the trap through the electrode 306 into the detector 118 . Thus, to selectively analyze ions of different mass-to-charge ratios, voltage source 106 (under the control of controller 108) varies the magnitude of the potential applied to electrodes 302 in a gradual manner. As the magnitude of the applied potential changes, ions of different mass-to-charge ratios are ejected from ion trap 104 and detected by detector 118 .

Electrodes 302, 304, and 306 within ion trap 104 are typically formed from conductive materials such as stainless steel, aluminum, or other metals. Spacers 308 and 310 are typically made of an insulating material such as ceramic, Teflon (for example, fluorinated polymer materials), rubber or various plastics.

The central openings in end cap electrodes 304 and 306 , in center electrode 302 , and in spacers 308 and 310 may have the same diameter and/or shape or different diameters and/or shapes. For example, in the embodiment shown in FIG. 3A , the central openings in electrode 302 and spacers 308 and 310 have a circular cross-sectional shape and diameter c ₀ . And the end cap electrodes 304 and 306 have a central opening with a circular cross-sectional shape and a diameter c ₂ <c ₀ . As shown in FIG. 3A, the openings in the electrodes and spacers are axially aligned with the axis 318 such that when the electrodes and spacers are assembled into the sandwich structure, the openings in the electrodes and spacers form an axis extending through the ion trap 104. to the mouth.

In general, the diameter c ₀ of the central opening in electrode 302 can be selected as desired to achieve a particular target resolving power when selectively ejecting ions from ion trap 104 and also to control the overall internal volume of mass spectrometer 100 . In certain embodiments, c0 is about _0.6 mm or greater (e.g., 0.8 mm or greater, 1.0 mm or greater, 1.2 mm or greater, 1.4 mm or greater, 1.6 mm or greater, 1.8 mm or more). _The diameter c2 of the central opening in the end cap electrodes 304 and 306 can also be selected as desired to achieve a specific target resolving power when ejecting ions from the ion trap 104 and to ensure proper confinement of ions that are not ejected. _In certain embodiments, c2 is about 0.25 mm or greater (eg, 0.35 mm or greater, 0.45 mm or greater, 0.55 mm or greater, 0.65 mm or greater, 0.75 mm or greater).

The axial length c ₁ of the combined openings in electrode 302 and spacers 308 and 310 may also be selected as desired to ensure proper ion confinement and achieve a specific target resolving power of ions as they are ejected from ion trap 104 . In some embodiments, _c is about 0.6 mm or greater (e.g., 0.8 mm or greater, 1.0 mm or greater, 1.2 mm or greater, 1.4 mm or greater, 1.6 mm or greater, 1.8 mm or more).

It has been empirically determined that the resolving power of mass spectrometer 100 is greater when c ₀ and c ₁ are chosen such that c ₁ /c ₀ is greater than 0.83. Thus, in some embodiments, c ₀ and c ₁ are selected such that the value of c ₁ /c ₀ is 0.8 or greater (e.g., 0.9 or greater, 1.0 or greater, 1.1 or greater, 1.2 or greater large, 1.4 or greater, 1.6 or greater).

Due to the relatively small size of ion trap 104, the number of ions that can be simultaneously trapped within ion trap 104 is limited by several factors. One such factor is space charge interactions between ions. As the density of trapped ions increases, the average spacing of trapped circulating ions decreases. As the ions (which can be either positively or negatively charged) are forced closer together, the magnitude of the repulsive force of the trapped ions increases.

To overcome limitations in the number of ions that can be simultaneously trapped within ion trap 104 and to increase the capacity of mass spectrometer 100, in some embodiments, mass spectrometer 100 may include an ion trap with multiple chambers. FIG. 3B shows a schematic diagram of an ion trap 104 having a plurality of ion chambers 330 arranged in a hexagonal array. Each chamber 330 functions in the same manner as ion trap 104 in FIG. 3A and includes two end cap electrodes and a cylindrical center electrode. Cap electrode 304 and a portion of cap electrode 306 are shown in FIG. 3B . End cap electrode 304 is connected to voltage source 106 through connection point 334 , and end cap electrode 306 is connected to voltage source 106 through connection point 332 .

FIG. 3C is a schematic cross-sectional view of FIG. 3B along section line A-A. It shows each of the five ion chambers 330 descending along section line A-A. Voltage source 106 is connected to center electrode 302 via a single connection point (not shown in FIG. 3C ). As a result, by applying an appropriate potential to electrodes 302 , voltage source 106 (under the control of controller 108 ) can simultaneously trap ions within each chamber 330 and eject ions of a selected mass-to-charge ratio from each chamber 330 .

In some embodiments, the number of ion chambers 330 in ion trap 104 may match the number of apertures formed in end cap electrode 304 . As described in Section II, the end cap electrode 304 may generally include one or more apertures. When the end cap electrode 304 includes multiple apertures, the ion trap 104 may also include multiple ion chambers 330 such that each aperture formed in the end cap electrode 304 corresponds to a different ion chamber 330 . In this way, ions generated within ion source 102 can be efficiently collected by ion trap 104 and trapped within ion chamber 330 . As described above, the use of multiple chambers reduces space charge interactions between trapped ions, increasing the trapping capacity of ion trap 104 . In general, the location and cross-sectional shape of ion chamber 330 may be the same as the arrangement and shape of apertures 240 and 294 discussed in Section II.

As an example, referring to FIG. 3B , the end cap electrode 304 includes a plurality of small holes arranged in a hexagonal array. Each aperture formed in electrode 304 matches a corresponding ion chamber 330, and thus, ion chambers 330 are also arranged in a hexagonal array.

In some embodiments, the number, arrangement, and/or cross-sectional shape of the ion chambers 330 do not match the arrangement of the apertures in the end cap electrode 304 . For example, end cap electrode 304 may include only one or a small number of apertures 294 , while ion trap 304 may include multiple ion chambers 330 . Because the use of multiple ion chambers 330 increases the trapping capacity of ion trap 104 , using multiple ion chambers may provide advantages even if the arrangement of the ion chambers does not match the arrangement of the apertures in end cap electrode 304 .

Additional features of ion trap 104 are disclosed, for example, in US Patent No. 6,469,298, US Patent No. 6,762,406, and US Patent No. 6,933,498, each of which is incorporated herein by reference in its entirety.

IV voltage source

Voltage source 106 provides operating power and potential to components of mass spectrometer 100 based on signals transmitted by controller 108 on control line 127e. As discussed above in Section I, the main advantages of the mass spectrometer disclosed herein are its compact size and significantly reduced power consumption relative to conventional mass spectrometers. While mass spectrometer 100 can generally be operated from a variety of voltage sources, it is advantageous to reduce power consumption of mass spectrometer 100 as much as possible if voltage source 106 is a high efficiency source.

However, efficient voltage sources that are small in size and capable of generating a voltage sufficient to drive the components of mass spectrometer 100 are not readily available commercially. 4A shows a schematic diagram of an embodiment of a high efficiency voltage source 106 configured to provide a high voltage RF signal 482 applied to the center electrode 302 of the ion trap 104 . During operation, voltage source 106 may amplify the voltage received from power supply 440 while modifying the waveform of high voltage RF signal 482 to suit a particular mass spectrometer measurement.

The design of power supply 106 allows mass spectrometer 100 to operate with high power efficiency throughout the various scan phases of high voltage RF signal 482 . At each stage, power efficiency is defined as the ratio of input electrical power to output electrical power. In some embodiments, the efficiency of the power supply 106 may be 40% or higher (e.g., 50% or higher, 60% or higher, 70% or higher, 80% or higher) in all stages of voltage amplification , 90% or higher). In contrast, conventional power amplifiers (emitter follower or class A amplifiers) typically have maximum efficiency at the highest amplification stage, but have significantly reduced efficiency at lower amplification stages. Therefore, conventional power amplifiers may be inefficient and unsuitable for applications requiring sweep voltage amplification.

In addition to operating efficiently, voltage source 106 allows a relatively low power source (eg, a battery) to provide the power and potential needed to activate various components of mass spectrometer 100 . As a result, mass spectrometer 100 has a compact shape and is lighter than conventional mass spectrometers.

Referring to FIG. 4A , the voltage source 106 includes a proportional-integral-derivative (PID) control loop 420 , a switching power supply 430 , an optional linear regulator 450 , a class D amplifier 460 , and a resonant circuit 480 . In some embodiments, the various components of voltage source 106 may be integrated into a module that may be inserted into support base 140 . This allows the voltage source 106 to be easily replaced with another module if it is defective. Alternatively, in some embodiments, any or more components of voltage source 106 may be implemented as separate modules and individually replaceable. In some embodiments, some or all components may be mounted directly to support base 140 . Each of the components shown in FIG. 4A is relatively low cost and generally commercially available, which allows the voltage source 106 to be manufactured in a cost effective manner.

During operation, PID control loop 420 receives modulation signal 412 from modulation signal generator 410 , which may or may not be a component of voltage source 106 . FIG. 4B shows an example of a modulated signal 412, where the amplitude variation (ie, envelope) of the signal is shown as a function of time. The envelope of the modulated signal 412 is approximately related to the envelope of the output high voltage RF signal 482 . Based on modulation signal 412, PID control loop 420 sends control signals 422 and 424 to switching mode power supply 430 and linear regulator 450 (if present), respectively.

The switching mode power supply 430 is configured to receive an input power signal 442 from a power source 440, which may include a battery (eg, a lithium-ion, lithium-polymer, nickel-cadmium, or nickel-metal hydride battery). The voltage provided by power supply 440 is typically between 0.5V and about 13V. As an example, the voltage may be about 7.2V. Switching mode power supply 430 amplifies input power signal 442 based on control signal 422 to produce modulated voltage signal 432 which is sent to linear regulator 450 (if present). An example of modulated voltage signal 432 is shown in FIG. 4C. Modulation voltage signal 432 typically has a magnitude between 0V and about 25V.

In some embodiments, the switched mode power supply 430 includes a switching regulator for high efficiency power amplification. During operation, the input power signal 442 may be less than, equal to, or greater than the output voltage signal 432 . This feature is particularly advantageous when the power source 440 is a battery. Unlike a linear power supply, a switched mode power supply 430 (which is a non-linear amplifier) can dissipate little or no power when switching between states of amplification, resulting in high power conversion. Additionally, switching mode power supplies 430 are generally more compact and lighter than conventional linear power supplies due to the smaller internal transformer size and weight.

Linear regulator 450 is optionally included in voltage source 106 . If linear regulator 150 is not present in voltage source 106 , then modified voltage signal 432 is sent from switching mode power supply 430 directly to class D amplifier 460 . Alternatively, when linear regulator 450 is present in voltage source 106 , linear regulator 150 receives modulation voltage signal 432 from switching mode power supply 430 and control signal 424 from PID control loop 420 .

Linear regulator 450 functions to filter irregularities in modified voltage signal 432 . Filtered voltage signal 442 from linear regulator 450 is received by D amplifier 442 . Typically, the linear regulator 450 comprises a low dropout voltage regulator, wherein a constant low dropout voltage ensures that the overall efficiency of the voltage source 106 drops only slightly due to the presence of the linear regulator 450 . In some embodiments, the control signal 424 received by the linear regulator 450 is used to modify the envelope of the output voltage signal 442 to be suitable for measuring the mass spectrum of a particular substance.

A reference wave generator 470 is optionally included in the voltage source 106 . If present, reference wave generator 470 provides reference wave signal 472 to class D amplifier 460 . Generally, the reference wave signal 472 has a frequency in the radio frequency range (eg, from about 0.1 MHz to about 50 MHz). For example, in some embodiments, the reference wave signal 472 may have a frequency of 1 MHz or higher, 2 MHz or higher, 4 MHz or higher, 6 MHz or higher, 8 MHz or higher, 15 MHz or higher, 30 MHz or higher )Frequency of.

FIG. 4D shows an example of a reference wave signal 472 . In FIG. 4D, reference wave signal 472 is a square wave. More generally, however, reference wave generator 470 may generate reference wave signal 472 of various different waveforms. In some embodiments, for example, reference wave signal 472 may correspond to any of a triangle wave, a sine wave, or a near-sine wave.

Class D amplifier 460 receives both reference wave signal 472 (if reference wave generator 470 is present) and filtered voltage signal 442 (or altered voltage signal 432 if linear regulator 450 is not present) and generates modulation from these input signals RF signal 462 . An example of modulated RF signal 462 is shown in FIG. 4E. In this example, the time interval of signal 462 is about 10 ms. The magnitude of signal 462 varies between 0V and about 30V. The frequency of the carrier in the RF signal 462 is the same or approximately the same as the frequency of the reference wave signal 472 . The envelope of RF signal 462 (eg, represented by the dashed line in FIG. 4E ) is the same or approximately the same as the envelope of filtered voltage signal 442 (or modified voltage signal 432 ).

FIG. 4F shows a schematic diagram of an embodiment of a class D amplifier 460 . Class D amplifier 460 includes a pair of transistors 441 . Within class D amplifier 460 , reference wave signal 472 is envelope modulated by filtered voltage signal 442 (or altered voltage signal 432 ) to generate RF signal 462 .

RF signal 462 is received by resonant circuit 480, also shown schematically in Figure 4F. Resonant circuit 480 includes inductor 486 and capacitor 488 . In some embodiments, the locations of inductor 486 and capacitor 488 may be swapped relative to those shown in Figure 4F. The inductance value of inductor 486 and the capacitance value of capacitor 488 are generally selected such that the resonant frequency of circuit 480 approximately matches the frequency of reference wave signal 472 .

In some embodiments, resonant circuit 480 has a Q factor of 60 or greater (eg, 80 or greater, 100 or greater). When RF signal 462 is applied to resonant circuit 480 , a high voltage RF signal 482 is generated across capacitor 488 . In general, the waveform of the high voltage RF signal 482 is the same or approximately the same as the waveform of the RF signal 462 except that the amplitude of the high voltage RF signal 482 is significantly greater than the amplitude of the RF signal 462 . For example, in some embodiments, the maximum magnitude of the high voltage RF signal 482 is 100V or higher (eg, 500V or higher, 1000V or higher, 1500V or higher, 2000V or higher). In general, the high Q factor of resonant circuit 480 allows a large magnitude voltage to be generated in RF signal 482 .

The combination of class D amplifier 462 and resonant circuit 480 is advantageous for several reasons, including low power consumption and frequency regulation. Another important advantage is the fact that a purely sinusoidal reference wave signal 472 is not required. In contrast, the combination of the class D amplifier 462 and the resonance circuit 480 can use a reference wave signal having a different waveform. Certain waveforms such as square waves can often be generated with higher fidelity than pure sinusoidal waveforms. As a result, the combination of the class D amplifier 462 and the resonant circuit 480 allows operation with a high stability reference wave signal.

Returning to FIG. 4A , the high voltage RF signal 482 may be monitored by an optional signal monitor 490 which may or may not be present in the voltage source 106 . Signal monitor 490 receives feedback signal 484 from resonant circuit 480 , which signal is typically a lower amplitude replica of high voltage RF signal 482 . Although the feedback signal 484 generally has a smaller magnitude than the high voltage RF signal 482 , at all points the magnitude of the feedback signal 484 is generally proportional to the magnitude of the high voltage RF signal 482 .

The feedback signal received by the signal monitor 490 from the resonant circuit may be communicated as a control signal 492 to the PID control loop 420 and/or the reference wave generator 470 . Based on control signal 492 , PID control loop 420 may send modified control signals 422 and 424 to switching mode power supply 430 and linear regulator 450 to optimize the waveform and amplitude of high voltage RF signal 482 . For example, PID control loop 420 may alter the envelope of modified voltage signal 432 based on control signal 492 to maximize the magnitude of high voltage RF signal 482 .

In some embodiments, the resonant frequency of resonant circuit 480 may not exactly match the frequency of reference wave signal 472 . For example, this may occur because the inductance value of the inductor 486 and/or the capacitance value of the capacitor 488 are inaccurate. Additionally, the inductance of inductor 486 and/or the capacitance of capacitor 488 may change over time. This can happen, for example, if class D amplifier 460 distorts the output frequency of RF signal 462 such that the frequency of RF signal 462 no longer matches the frequency of reference signal wave 472 . This mismatch could potentially reduce the efficiency of voltage source 106 because resonant circuit 480 is no longer an effective resonator for RF signal 462 .

Several techniques can be implemented to compensate for this mismatch. In some embodiments, the frequency of reference wave signal 472 may be swept by reference wave generator 470 while monitoring control signal 492 . The reference wave generator 470 may select the optimal frequency of the reference wave signal 472 as the frequency that maximizes the amplitude of the control signal 492 .

In some embodiments, the capacitance of capacitor 488 may be varied in resonant circuit 480 to determine which capacitance value maximizes the magnitude of control signal 492 . To this end, capacitor 488 may be a variable capacitor.

The foregoing techniques for compensating for frequency mismatches can be implemented directly in hardware, software, or both. For example, controller 108 may be configured to perform one or more of these methods to compensate for frequency mismatch. Controller 108 may be configured to automatically and/or continuously perform these methods to continuously optimize frequency matching. Alternatively, the controller 108 may be configured to perform the methods only upon receiving instructions from the user, eg, when the user activates a control on the user interface 112 . When executed by the controller 108, the techniques disclosed herein for compensating for frequency mismatches are typically within 5 minutes or less (e.g., 3 minutes or less, 2 minutes or less, 1 minute or less) Finish.

A high voltage RF signal 482 is applied to ion trap 104 (eg, center electrode 302 of ion trap 104 ) to selectively eject trapped ions for detection by detector 118 . The range of mass-to-charge ratios that can be analyzed using ion trap 104 depends on, among other factors, the profile (eg, envelope and maximum amplitude) of RF signal 482 . By varying these characteristics of the RF signal 482, the voltage source 106 (under the control of the controller 108) can select the range of mass-to-charge ratios to be analyzed.

In some embodiments, voltage source 106 may include multiple reference wave generators 470 and/or multiple resonant circuits 480 . During operation, a particular reference wave generator 470 and particular resonant circuit 480 combination may be selected by controller 108 to generate a suitable high voltage RF signal 482 for analysis of a particular mass-to-charge ratio range using ion trap 104 . To change the range of analyzed mass-to-charge ratios, the controller 108 selects a different reference wave generator 470 and/or resonant circuit 480 .

V detector

Detector 118 is configured to detect charged particles exiting ion trap 104 . Charged particles can be positive ions, negative ions, electrons or a combination of these.

A wide range of different detectors can be used in mass spectrometer 100 . FIG. 5A shows an embodiment of a detector 118 including a Faraday cup 500 . The Faraday cup 500 has a circular base 502 and a cylindrical sidewall 504 . In general, the shape and geometry of Faraday cup 500 can be varied to optimize the sensitivity and resolution of mass spectrometer 100 .

For example, base 502 may have various cross-sectional shapes, including square, rectangular, oval, circular, or any other regular or irregular shape. The base 502 may be flat or curved, for example.

FIG. 5B shows a side view of Faraday cup 500 . In some embodiments, the length 506 of the sidewall 504 can be 20 mm or less (eg, 10 mm or less, 5 mm or less, 2 mm or less, 1 mm or less, or even 0 mm). In general, length 506 may be selected according to various criteria, including maintaining the compactness of mass spectrometer 100, providing desired selectivity during detection of charged particles, and resolution. In some embodiments, sidewall 504 conforms to the cross-sectional shape of base 502 . More generally, though, the sidewall 504 is not required to conform to the shape of the base 502 and may have various cross-sectional shapes that differ from the shape of the base 502 . Also, the sidewall 504 does not have to be cylindrical in shape. In some embodiments, for example, sidewall 504 may be curved along the axis of Faraday cup 500 .

In general, the Faraday cup 500 can be relatively small. The largest dimension of the Faraday cup 500 corresponds to the largest linear distance between any two points on the cup. In certain embodiments, for example, the Faraday cup 500 has a maximum distance of 30 mm or less (eg, 20 mm or less, 10 mm or less, 5 mm or less, 3 mm or less).

Typically, the thickness of the base 502 and/or the thickness of the sidewall 504 is selected to ensure efficient detection of charged particles. In certain embodiments, for example, the thickness of base 502 and/or sidewall 504 is 5 mm or less (eg, 3 mm or less, 2 mm or less, 1 mm or less).

The side walls 504 and base 502 of the Faraday cup 500 are typically formed from one or more metals. Metals that can be used to fabricate the Faraday cup 500 include, for example, copper, aluminum, and silver. In some embodiments, Faraday cup 500 may have one or more coatings on the surface of base 502 and/or sidewall 504 . Coatings can be formed from materials such as copper, aluminum, silver and gold.

During operation of mass spectrometer 100 , charged particles may drift or accelerate into Faraday cup 500 as they are ejected from ion trap 104 . Once in the Faraday cup 500, the charged particles are trapped on the surfaces of the Faraday cup 500 (eg, the surfaces of the base 502 and/or sidewalls 504). Charged particles trapped by either base 502 or sidewall 504 generate a current that is measured (eg, by circuitry within detector 118 ) and reported to controller 108 . If the charged particles are ions, the measured current is the ion current and its magnitude is proportional to the abundance cost of the ion being measured.

To obtain a mass spectrum of an analyte, the magnitude of the potential applied to the center electrode 302 of the ion trap 104 is varied (e.g., a variable amplitude signal, high voltage RF signal 482 is applied) to selectively eject a specific mass from the ion trap 104. Charged ions. For each change in magnitude corresponding to a different mass-to-charge ratio, the ion current of the ejected ions corresponding to the selected mass-to-charge ratio is measured using the Faraday cup 500 . The measured ion current as a function of the potential applied to the electrode 302 - which corresponds to a mass spectrum - is reported to the controller 108 . In some embodiments, the controller 108 converts the applied voltage to a specific mass-to-charge ratio for the ion trap 104 based on the algorithm and/or calibration information for the ion trap 104 .

After the charged particles are ejected from the ion trap 104 through the end cap electrode 306 , the charged particles may be accelerated to impact the detector 118 by creating an electric field between the detector 118 and the end cap electrode 306 . In some embodiments, where detector 118 includes Faraday cup 500 , for example, the conductive surface of Faraday cup 500 is held at ground potential established by voltage source 106 and a positive potential is applied to end cap electrode 306 . With these applied potentials, positive ions are repelled from the end cap electrode 306 to the grounded conductive surface of the Faraday cup 500 . Furthermore, electrons flowing through the end cap electrode 306 are attracted to the end cap electrode 306 and thus do not strike the Faraday cup 500 . Therefore, this configuration results in an improved signal-to-noise ratio. More generally, Faraday cup 500 may be at a different potential than ground as long as it is at a lower potential than end cap electrode 306 in this configuration.

In certain embodiments, it is desirable to detect negatively charged particles (eg, negative ions and/or electrons). To detect such particles, Faraday cup 500 is biased at a higher voltage than end cap electrode 306 to attract negatively charged particles to Faraday cup 500 .

In some embodiments, detector 118 may include a Faraday cup 500 having two regions separated by an insulating region. Different bias potentials can be applied to each region. For example, FIG. 5C shows a Faraday cup 500 having two conductive regions 510 and 520 separated by an insulating region 530 . By grounding end cap electrode 306 and applying positive and negative bias voltages to regions 510 and 520, respectively, region 510 can detect negatively charged particles and region 520 can detect positively charged particles. This configuration can provide additional information during the measurement of mass spectra, since positively and negatively charged ions can be detected simultaneously. Alternatively, by applying a bias potential to first activate one of regions 510 and 520, and then activate the other region, measurements of positively and negatively charged ions may be performed sequentially. Alternatively, in some embodiments, detector 118 may include two Faraday cups 500, with different bias voltages applied to each Faraday cup 500 for detecting positively and negatively charged ions.

In some embodiments, detector 118 may be secured directly to housing 122 . For example, FIG. 5C shows housing 122 that includes one or more electrodes 550 and 552 that contact Faraday cup 500 . Alternatively, in some embodiments, one or more electrodes 550 and 552 may be attached directly to Faraday cup 500 . In some embodiments, one electrode may be used to bias the Faraday cup 500 while the other electrode may be used to measure the current generated by the Faraday cup 500 . Alternatively, in some embodiments, the same electrodes may be used to apply the bias voltage and measure the current.

In some embodiments, housing 122 may be configured such that detector 118 is easily installed or removed. For example, as shown in FIG. 5C , housing 122 includes openings into which Faraday cup 500 may be securely mounted and retained by clamping elements 540 (eg, screws or other fasteners). This is particularly advantageous if the Faraday cup 500 is broken or contaminated, which can be determined by detecting plasma peaks during mass spectrometry measurements as described above. A contaminated Faraday cup 500 can be replaced by removing the cup 500 from the opening in the housing 122, and installing the replacement. Contaminated Faraday cups can be repaired or cleaned up on site. For example, Faraday cup 500 may be baked in a portable oven so that sticky particles on the surface of Faraday cup 500 are evaporated. The cleaned Faraday cup can be inserted back into housing 122 . This replaceability allows for minimal downtime of mass spectrometer 100, even if certain components of the mass spectrometer become contaminated. In some embodiments, a contaminated Faraday cup 500 may be cleaned by heating (eg, applying a high current through base 502 and sidewall 504 ) while the Faraday cup remains installed in housing 122 . Contaminated particles released from the surface of base 502 and/or sidewall 504 may be removed by pressure regulation subsystem 120 .

In some embodiments, Faraday cup 500 may be implemented as a component of pluggable, replaceable module 148, as described in Section I. In a modular configuration, the Faraday cup 500 may be formed, for example, as a groove in a plate of conductive material. The plate can be attached directly to another component of the module 148, such as the ion trap 104, so that the small holes in the end cap electrodes 306 align with the grooves, and the ions ejected from the ion trap 104 enter the Faraday cup directly. Modules with different Faraday cup diameters can be used to provide selective detection of different types of analytes.

Figure 5D shows detector 118, which includes an array of faradic cup detectors 500, which may or may not be monolithically formed. A detector array may be advantageous, for example, when ion trap 104 includes an array of ion chambers 330 . The end cap electrode 306 may include a plurality of apertures 560 aligned with each ion chamber such that ions ejected from each chamber pass through only one of the apertures 560 . Upon passing through one of the apertures 560 , the ions are incident on one of the cups in the array of Faraday cup detectors 500 . This method based on array ejection and detection of ions can significantly increase the efficiency of detecting ejected ions. In the array geometry shown in FIG. 5D , each Faraday cup 500 may be sized to conform to the size of each aperture 560 formed in the end cap electrode 306 .

In some embodiments, a biased repulsion grid or magnetic field may be placed in front of the Faraday cup 500 or to prevent emission of secondary charged particles, which would distort measurements of particles ejected from the ion trap 104 . Alternatively, in some embodiments, secondary emissions from the Faraday cup 500 can be used to detect ejected ions.

While the foregoing discussion has revolved around Faraday cup detectors for low power operation and compact size, a variety of other detectors may be used in mass spectrometer 100 more generally. For example, other suitable detectors include electron multipliers, photomultiplier tube detectors, scintillation detectors, image current detectors, Daly detectors, fluorescence-based detectors, and detectors in which incident charged particles generate photons that are subsequently detected. Other detectors (ie, detectors employing a charge-to-photon transduction mechanism).

VI pressure regulation subsystem

Pressure regulation subsystem 120 is generally configured to regulate the gas pressure in gas circuit 128 , which includes the internal volumes of ion source 102 , ion trap 104 , and detector 118 . As described above in Section I, during operation of mass spectrometer 100, pressure regulation subsystem 120 maintains the gas pressure within mass spectrometer 100 at 100 mTorr or greater (e.g., 200 mTorr or greater, 500 mTorr or greater, 700 mTorr or greater large, 1Torr or greater, 2Torr or greater, 5Torr or greater, 10Torr or greater), and/or 100Torr or less (e.g., 80Torr or less, 60Torr or less, 50Torr or less, 40Torr or smaller, 30Torr or smaller, 20Torr or larger).

In some embodiments, pressure regulation subsystem 120 maintains the gas pressure within certain components of mass spectrometer 100 within the ranges described above. For example, pressure regulation subsystem 120 can maintain the gas pressure in ion source 102 and/or ion trap 104 and/or detector 118 between 100 mTorr and 100 Torr (e.g., between 100 mTorr and 10 Torr, between 200 mTorr and 10 Torr , between 500mTorr and 10Torr, between 500mTorr and 50Torr, between 500mTorr and 100Torr). In certain embodiments, the gas pressures in at least two of ion source 102, ion trap 104, and detector 118 are the same. In some embodiments, the air pressure is the same in all three components.

In some embodiments, the gas pressures in at least two of ion source 102, ion trap 104, and detector 118 differ by a relatively small amount. For example, pressure regulation subsystem 120 can maintain the gas pressure of at least two of ion source 102, ion trap 104, and detector 118 at 100 mTorr or less (e.g., 50 mTorr or less, 40 mTorr or less, 30 mTorr or less, 20mTorr or less, 10mTorr or less, 5mTorr or less, 1mTorr or less). In certain embodiments, the gas pressures in all three of ion source 102, ion trap 104, and detector 118 differ by 100 mTorr or less (e.g., 50 mTorr or less, 40 mTorr or less, 30 mTorr or less, 20 mTorr or less, 10mTorr or less, 5mTorr or less, 1mTorr or less).

As shown in FIG. 6A , the pressure regulation subsystem 120 may include a scroll pump 600 having a pump housing 606 with one or more alternating scroll flanges 602 and 604 . Relative orbital motion between scroll flanges 602 and 604 traps gas and liquid, resulting in a pumping action. In some embodiments, scroll flange 604 may be fixed while scroll flange 602 orbits eccentrically, with or without rotation. In some embodiments, both scroll flanges 602 and 604 move off-center of rotation. FIG. 6B shows a schematic view of the scroll flange 602 . Examples of vortex flange geometries include, but are not limited to, involutes, Archimedes spirals, and mixed curves.

The orbital motion of scroll flanges 602 and 604 allows scroll pump 600 to generate only a small amount of vibration and low noise during operation. Accordingly, the scroll pump 600 can be directly coupled to the ion trap 104 and introduce no substantial adverse effects during mass spectrometry measurements. To further reduce vibration coupling, the orbiting scroll flange 602 can be balanced with a simple mass. Because scroll pumps have few moving parts and generate very little vibration, the reliability of these pumps is usually very high.

Scroll pump 600 is generally compact in size and light in weight. In certain embodiments, for example, the largest dimension of the scroll pump 600 (e.g., the largest linear distance between any two points on the scroll pump 600) is less than 10 cm (e.g., less than 8 cm, less than 6 cm, less than 5 cm, less than 4 cm, less than 3cm, less than 2cm). In certain embodiments, the scroll pump 600 weighs less than 1.0 kg (eg, less than 0.8 kg, less than 0.7 kg, less than 0.6 kg, less than 0.5 kg, less than 0.4 kg, less than 0.3 kg, less than 0.2 kg).

The small size and weight of scroll pump 600 allows it to be incorporated into mass spectrometer 100 in various configurations. In some embodiments, scroll pump 600 (as part of pressure regulation subsystem 120 ) may be mounted directly to support base 140 (eg, a printed circuit board) as shown, for example, in FIGS. 1D and 1E . In certain embodiments, scroll pump 600 (as part of pressure regulation subsystem 120 ) may be implemented as a pluggable, replaceable component of module 148 and may be attached directly to one or other of the other components of module 148 Multiple, such as ion source 102 , ion trap 104 and/or detector 118 .

FIG. 6A shows a scroll pump 600 mounted directly to a printed circuit board 608 . The pump inlet 610 is directly connected to the pump inlet 620 of the manifold 121 . The scroll pump 600 is secured to the plate 608 by a fastening member 630 and a fixing member 632, which may be positioned at a distance of 1 cm or more (e.g., 2 cm or more) from the positions of the pump inlets 610 and 620. , 3cm or greater, 4cm or greater), thereby reducing the vibration coupling between the pump 600 and the plate 608. Alternatively, instead of a direct connection between pump 600 and manifold 121 , in some embodiments conduits (eg, flexible and rigid tubing) may connect pump inlet 610 to pump inlet 620 .

Scroll pumps suitable for use in pressure regulation subsystem 120 are commercially available from, for example, Agilent Technologies (Santa Clara, CA). In addition to scroll pumps, other pumps may be used in pressure regulation subsystem 120 . Examples of suitable pumps include diaphragm pumps, diaphragm pumps and Roots blower pumps.

The use of small simple mechanical pumps offers several advantages over the pumping schemes used in traditional mass spectrometers. In particular, conventional mass spectrometers typically use multiple pumps, at least one of which operates at a high rotational frequency. Large mechanical pumps operating at high rotational frequencies generate mechanical vibrations that couple into other components of the mass spectrometer, creating unwanted noise in the measurement information. Additionally, even if measures are taken to isolate such vibrating components, the isolation mechanism typically increases the size of the mass spectrometer, sometimes relatively significantly. Furthermore, large pumps operating at high frequencies consume large amounts of electrical power. Accordingly, conventional mass spectrometers include large power supplies to meet these requirements, further increasing the size of such instruments.

Instead, a single mechanical pump such as a scroll pump can be used in the mass spectrometers disclosed herein to control the air pressure in each component of the system. By operating the mechanical pump at a relatively low rotational frequency, the mechanical coupling of vibrations into other components of the mass spectrometer can be much reduced or eliminated. Furthermore, by operating at a low rotational frequency, the amount of power consumed by the pump is so small that its proper requirements can be met by the voltage source 106 .

It has been empirically determined that, in certain embodiments, by operating a single mechanical pump at a frequency of less than 6000 revolutions per minute (e.g., less than 5000 revolutions per minute, less than 4000 revolutions per minute, less than 3000 revolutions per minute, less than 2000 revolutions per minute) , the pump is able to maintain the desired gas pressure within the mass spectrometer 100 and at the same time its power consumption requirements can be met by the voltage source 106 .

VII shell

As described in Section I, mass spectrometer 100 includes a housing 122 that encloses the components of the mass spectrometer. FIG. 7A shows a schematic view of an embodiment of housing 122 . Sample inlet 124 is integrated into housing 122 and is configured to introduce gas particles into gas path 128 . Also integrated into housing 122 is display 116 and user interface 112 .

In some embodiments, display 116 is a passive or active liquid crystal or light emitting diode (LED) display. In some embodiments, display 116 is a touch screen display. Controller 108 is connected to display 116 and can use display 116 to display various information to a user of mass spectrometer 100 . Displayed information may include, for example, information regarding the identity of one or more substances scanned by mass spectrometer 100 . This information may also include mass spectra (eg, measurements of the abundance of ions detected by detector 118 as a function of mass-to-charge ratio). Additionally, the displayed information may include operating parameters and information for mass spectrometer 100 (e.g., measured ion currents, voltages applied to various components of mass spectrometer 100, current modules 148 associated with mass spectrometer 100, etc. associated name and/or identity, alerts associated with substances identified by mass spectrometer 100, and defined user preferences for operating mass spectrometer 100). Information such as defined user preferences and operating settings may be stored in storage unit 114 and retrieved by controller 108 for display.

In some embodiments, user interface 112 includes a series of controls integrated into housing 122, as shown in FIG. 7A. Controls that may be activated by a user of mass spectrometer 100 may include buttons, sliders, rockers, switches, and other similar controls. By activating controls of user interface 112, a user of mass spectrometer 100 can initiate various functions. For example, in some embodiments, activation of one of the controls initiates a scan of mass spectrometer 100 during which the mass spectrometer draws a sample (e.g., gas particles) through sample inlet 124, from which ions are generated, The ions are then captured and analyzed using ion trap 104 and detector 118 . In some embodiments, activation of one of the controls resets mass spectrometer 100 prior to performing a new scan. In some embodiments, mass spectrometer 100 includes a control that restarts mass spectrometer 100 when activated by a user (e.g., after changing a component of mass spectrometer 100 such as module 148 and/or a filter connected to sample inlet 124) .

When display 116 is a touchscreen display, even a portion or all of user interface 112 may be implemented as a series of touchscreen controls on display 116 . That is, some or all of the controls of user interface 112 may be represented as touch-sensitive areas of display 116 that are activated by a user touching display 116 with a finger.

As described in Section I, in certain embodiments, mass spectrometer 100 includes a replaceable, pluggable module 148 that includes ion source 102 , ion trap 104 and (optionally) detector 118 . When mass spectrometer 100 includes pluggable modules 148 , housing 122 may include openings to allow a user to access the interior of housing 122 to replace modules 148 without removing housing 122 . FIG. 7B is a cross-sectional view of mass spectrometer 100 including pluggable module 148 . In FIG. 7B , the housing 122 includes an opening 702 and a partition 704 that seals the opening 702 . When module 148 is to be replaced, a user of mass spectrometer 100 may open bulkhead 704 to expose the interior of mass spectrometer 100 . The bulkhead 704 is positioned such that it provides direct access to the pluggable module 148 , allowing a user to unplug the module 148 from the support base 140 and install another module in place without removing the housing 122 . The user may then re-seal opening 702 by tightening bulkhead 704 .

In Figure 7B, the partition 704 is implemented in the form of a retractable door. More generally, however, a variety of baffles may be used to seal the opening in housing 122 . For example, in some embodiments, partition 704 may be implemented as a cover that is completely removable from housing 122 .

In general, mass spectrometer 100 can include a wide variety of different sample inlets 124 . For example, in some embodiments, sample inlet 124 includes an aperture configured to draw gas particles from the environment surrounding mass spectrometer 100 directly into gas path 128 . Sample inlet 124 may include one or more filters 706 . For example, in some embodiments, filter 706 is a HEPA filter and blocks dust and solid particles from entering mass spectrometer 100 . In certain embodiments, filter 706 includes a molecular sieve material that traps water molecules.

As previously discussed, conventional mass spectrometers operate at low internal gas pressures. To keep the gas pressure low, conventional mass spectrometers include one or more filters attached to the sample inlet. These filters are selective and filter out particles of a particular type of substance, such as atmospheric gas particles (eg, molecular nitrogen and/or oxygen molecules), to prevent them from entering the mass spectrometer. Filters can also be specifically tailored for specific classes of analytes, such as biomolecules, and can filter out other types of molecules. As a result, filters for conventional mass spectrometers, which can include pinch valves, and membrane filters formed from materials such as polydimethylsiloxane, which allows selective transport of species ) to filter an incoming stream of gas particles to remove specific types of particles from the stream. Without such filters, conventional mass spectrometers cannot operate because low internal air pressure cannot be maintained, and certain particles admitted to the mass spectrometer will prevent the operation of certain components. As an example, thermionic ion sources used in conventional mass spectrometers do not operate in the presence of modest concentrations of atmospheric oxygen.

The use of substance-specific filters in conventional mass spectrometers has several drawbacks. For example, because filters are selective, only small numbers of analytes can be analyzed without changing filters and/or operating conditions, which is troublesome. In particular, selecting the correct selectivity filter to reconfigure a mass spectrometer for a given analyte can be difficult for an untrained user of the mass spectrometer. Furthermore, the filters used in conventional mass spectrometers introduce a time delay because analyte particles do not diffuse instantaneously through the filter. Depending on the selectivity of the filter and the concentration of the analyte, a considerable delay is introduced between the time the analyte is first encountered and the time a sufficient number of analyte ions are detected to generate mass spectral information.

However, the mass spectrometers disclosed herein operate at higher pressures and it is not necessary to include filters such as membrane filters to maintain low gas pressure within the mass spectrometer. By operating without the use of filters of the type used in conventional mass spectrometers, the mass spectrometers disclosed herein can analyze larger quantities or different types of samples without significant reconfiguration, and can perform analyzes more quickly. Moreover, because the components of the mass spectrometers disclosed herein are generally insensitive to atmospheric gases such as nitrogen and oxygen, the mass spectrometer can permit these gases to accompany the particles of the analyte of interest, which significantly increases the speed of analysis and reduces the need for other components of the mass spectrometer (e.g., , the operating requirements of the pumping load of the pressure regulating subsystem 120).

Thus, in general, filters (eg, filter 706 ) used in mass spectrometers disclosed herein do not filter atmospheric gas particles (eg, nitrogen and oxygen molecules) in the flow of gas particles entering sample inlet 124 . Specifically, filter 706 allows at least 95% or more of atmospheric gas particles that encounter the filter to pass through.

The different types of filters 706 are replaceable and can be replaced by the user of mass spectrometer 100 if they become dirty or ineffective. In some embodiments, the mass spectrometer 100 may include a plurality of filters 706, and the user may selectively install any one or more of the filters according to the properties of the sample being analyzed.

In certain embodiments, sample inlet 124 may be configured to receive direct incidence of the species to be analyzed. For example, the filter 706 can be replaced by a sample injection port attached to the sample inlet 124 . During use of mass spectrometer 100 , species incident on sample inlet 124 through the sample inlet is introduced into gas path 128 , ionized by ion source 102 , and analyzed by ion trap 104 and detector 118 .

In certain embodiments, mass spectrometer 100 may include various sample introduction modules attached to housing 122 to introduce different types of analytes into mass spectrometer 100 . Sample introduction module 750 is shown schematically in Figure 7C. Module 750 is attached to housing 122 such that electrodes 752 in housing 122 establish an electrical connection to corresponding electrodes in module 750 . The electrodes 752 are connected to the controller 108 and the voltage source 106 on the support base 140 . The voltage source 106 can supply power to the module 750 through the electrodes 752 and the controller 108 can transmit and receive signals to/from the module 750 . When module 750 is attached to housing 122 (eg, using a bolt or keyed connection, or a magnetic attachment mechanism, or any of a variety of other attachment mechanisms), voltage source 106 automatically supplies power to activate module 750 . Once activated, the module 750 reports its identity to the controller 108, which may display information on the display 116 regarding the activated module. Controller 108 may retrieve configuration settings and other operating parameters from storage unit 114 such that mass spectrometer 100 is configured to automatically analyze samples introduced through module 750 .

In general, various sample introduction modules can be used with mass spectrometer 100 . For example, in some embodiments, module 750 is a steam heat absorption module. In certain embodiments, module 750 is a low temperature plasma module. In certain embodiments, module 750 is an electrospray ionization module. Each of these modules can be used interchangeably with mass spectrometer 100 to analyze a wide range of different samples.

In addition to replaceable modules 750, mass spectrometer 100 may also include various sensors. For example, in some embodiments, mass spectrometer 100 may include a limit sensor 708 coupled to controller 108 . Limit sensor 708 detects gas particles in the environment surrounding the mass spectrometer and reports the gas concentration to controller 108 . During user operation of mass spectrometer 100, controller 108 monitors the length of time and concentration of gas measured by limit sensor 708, and displays an alert to the user (e.g., via display 116) if the user's exposure to gas particles exceeds a threshold concentration or threshold time limit. ). Information regarding threshold exposure concentrations and time limits may be stored, for example, in storage unit 114 and retrieved by controller 108 . Example limit sensors that may be used in mass spectrometer 100 include flammable/LEL gas sensors, photoionization sensors, electrochemical sensors, and temperature and humidity sensors.

In some embodiments, mass spectrometer 100 may include explosion hazard sensor 710 . An explosion hazard sensor 710 connected to the controller 108 detects the presence of explosive substances in the vicinity of the mass spectrometer 100 . Threshold concentrations of various explosive substances may be stored in storage unit 114 and retrieved by controller 108 . During operation of mass spectrometer 100 , controller 108 may display an alert message to a user of mass spectrometer 100 via display 116 when the concentration of one or more explosive substances measured by sensor 710 exceeds a threshold. In some embodiments, the warning message may advise the user to stop using the mass spectrometer 100, or use it in a secondary shield (eg, cage) to prevent ignition of one or more explosive substances. Explosion hazard sensors that may be used with mass spectrometer 100 include, for example, combustible sensors, which are commercially available from MSA (Cranberry Township, PA) and RAE Systems (San Jose, CA).

The housing 122 is generally shaped so that it can be comfortably operated by a user with either or both hands. In general, housing 122 can have a wide range of different shapes. However, due to the selection and integration of the components of mass spectrometer 100 disclosed herein, housing 122 is generally compact. As shown in Figures 7A and 7B, regardless of the overall shape, housing 122 has _a maximum dimension a1 that corresponds to the longest linear distance between any two points on the outer surface of the housing. In certain embodiments, _a is 35 cm or less (e.g., 30 cm or less, 25 cm or less, 20 cm or less, 15 cm or less, 10 cm or less, 8 cm or less, 6 cm or less small, 4cm or less).

In addition, due to the selection of components within the mass spectrometer 100, the overall weight of the mass spectrometer 100 is significantly reduced relative to conventional mass spectrometers. In certain embodiments, for example, mass spectrometer 100 has a total weight of 4.5 kg or less (e.g., 4.0 kg or less, 3.0 kg or less, 2.0 kg or less, 1.5 kg or less, 1.0 kg or lighter, 0.5kg or lighter).

VIII mode of operation

In general, mass spectrometer 100 operates according to various different modes of operation. FIG. 8A is a flowchart 800 showing the general sequence of steps performed in different modes of operation to scan and analyze a sample. In a first step 802, the scanning of the sample is started. In some embodiments, the scan is initiated by a user of mass spectrometer 100 . For example, mass spectrometer 100 may be configured to operate in a "one-button" mode in which a user may initiate a scan of a sample simply by activating a control in user interface 112 . FIG. 8B illustrates an embodiment of mass spectrometer 100 in which user interface 112 includes a control 820 for starting a scan. When control 820 is activated by the user, a scan of the sample (shown as gas particles 822 in FIG. 8B ) is initiated.

In some embodiments, controller 108 may automatically initiate a scan based on one or more sensor readings. For example, when mass spectrometer 100 includes limit sensors such as photoionization detectors and/or LEL sensors, controller 108 may monitor the signals of these sensors. If a sensor indicates that a potential substance of interest has been detected, for example, controller 108 may initiate a scan. In general, a wide range of different sensor-like events or conditions can be used automatically by the controller 108 to initiate scanning.

In certain embodiments, mass spectrometer 100 may be configured to operate in a "continuous scan" mode. After the mass spectrometer 100 has been placed in the continuous scan mode, the scan is repeatedly started after a fixed time interval has expired. The time interval is configured by the user, and the value of the time interval may be stored in the storage unit 114 and retrieved by the controller 108 . Thus, in step 802 of FIG. 8A, when the mass spectrometer 100 is in the continuous scan mode, a scan is initiated by the mass spectrometer.

After the scan has started, the sample is introduced into mass spectrometer 100 at step 804 . A variety of different methods can be used to introduce the sample into the mass spectrometer. In certain embodiments, where the sample consists of gas particles (e.g., gas particles 822 in FIG. into the gas path 128). If the sample inlet 124 includes a filter 706, the gas particles pass through the filter, which removes dust and other solid materials from the gas particle stream. As disclosed above, the pressure regulation subsystem maintains the air pressure in the air circuit 128 at a level below atmospheric pressure. As a result, when valve 129 is open, gas particles 822 are drawn into sample inlet 124 by the pressure differential between gas line 128 and the environment surrounding mass spectrometer 100 . Alternatively or additionally, pressure regulation subsystem 120 may facilitate the flow of gas particles into mass spectrometer 100 .

In some embodiments, a sample can be introduced into mass spectrometer 100 via direct incidence. Mass spectrometer 100 may include a sample injection port connected to sample inlet 124 as disclosed above in Section VII. The sample injection port allows a user of mass spectrometer 100 to inject a sample directly into sample inlet 124 for analysis. Once incident, the sample enters gas path 128 .

In some embodiments, a sample in a partially ionized state can be drawn into mass spectrometer 100 by electrostatic or electrodynamic forces. For example, charged particles may be accelerated into mass spectrometer 100 (eg, through sample inlet 124 ) by applying suitable potentials to electrodes in mass spectrometer 100 .

Next, in step 806 , the sample is ionized in ion source 102 . As disclosed above, sample inlet 124 may be positioned at various locations along gas path 128 relative to other components of mass spectrometer 100 . For example, in some embodiments, sample inlet 124 is positioned such that gas particles introduced into mass spectrometer 100 first enter ion trap 104 from sample inlet 124 . In certain embodiments, sample inlet 124 is positioned such that gas particles introduced into mass spectrometer 100 first enter ion source 102 from sample inlet 124 . In certain embodiments, sample inlet 124 is positioned such that gas particles first enter detector 118 from sample inlet 124 . Furthermore, sample inlet 124 may be positioned such that gas particles entering mass spectrometer 100 enter gas path 128 at a point between ion source 102 and/or ion trap 104 and/or detector 118 .

After a sample (eg, gas particles 822 ) is introduced into mass spectrometer 100 at a point along gas path 128 , some of the gas particles enter ion source 102 . If the sample inlet 124 is not positioned such that the gas particles 822 enter the ion source 102 directly, then the movement of the gas particles 822 into the source 102 may be by diffusion. Once in the ion source 102, the controller 108 activates the ion source 102 to ionize the gas particles, as disclosed in Section II.

Next, the ions generated in step 806 are trapped in ion trap 104 in step 808 . As disclosed in Section II above, the movement of ions from ion source 102 to ion trap 104 typically occurs under the influence of an electric field generated between ion source 102 and ion trap 104 . Once within the ion trap 104 , the ions are trapped by the electric field within the trap and circulate within the opening in the center electrode 302 and between the end cap electrodes 304 and 306 . The electric field within ion trap 104 is generated under the control of controller 108 by voltage source 106, which applies a suitable potential to electrodes 302, 304, and 306 to generate a trapping field.

In step 810, circulating ions in ion trap 104 are selectively ejected from the trap. As discussed in Section III, selective ejection of ions from trap 104 occurs under the control of controller 108 , which sends a signal to voltage source 106 to vary the magnitude of the RF voltage applied to center electrode 302 . As the magnitude of the potential changes, the magnitude of the electric field at the inner center of the center electrode 302 also changes. In addition, as the magnitude of the field within the central electrode 302 changes, circulating ions with a specific mass-to-charge ratio fall out of the circulating orbit within the central electrode 302 and pass through one or more small holes in the end cap electrode 306 from the ion The well 104 is ejected. Controller 108 is configured to command voltage source 106 to sweep the magnitude of the applied potential according to a defined function (eg, a linear magnitude sweep) to selectively eject ions of a particular mass-to-charge ratio from ion trap 104 into detector 118 . The rate at which the potential is applied to sweep may be automatically determined by controller 108 (eg, to achieve a target resolving power of mass spectrometer 100 ), and/or may be set by a user of mass spectrometer 100 .

After ions have been selectively ejected from ion trap 104 , they are detected by detector 118 in step 812 . As disclosed in Section V, various detectors can be used to detect ions. For example, in some embodiments, detector 118 includes a faradic cup for detecting ejected ions.

For each mass-to-charge ratio selected by the magnitude of the potential applied to central electrode 302 in ion trap 104, detector 118 measures a current associated with the abundance of detected ions having the selected mass-to-charge ratio. The measured current is communicated to the controller 108 . As a result, the information received by the controller 108 from the detector 118 corresponds to the measured abundance of ions as a function of the mass-to-charge ratio of the ions. This information corresponds to the mass spectrum of the sample.

More generally, the controller 108 is configured to detect ions based on their mass-to-charge ratio, which means that the controller 108 detects or receives a signal related to the detection of ions and to the mass-to-charge ratio of the ions. In certain embodiments, controller 108 detects ions or receives information about ions directly as a function of mass-to-charge ratio. In some embodiments, the controller 108 detects ions or receives information about the ions as a function of another quantity, such as the potential applied to the ion trap 104, and is related to the mass-to-charge ratio of the ions. In all such embodiments, controller 108 detects ions based on mass-to-charge ratio.

In step 814 , the information received from detector 118 is analyzed by controller 108 . Generally, to analyze this information, controller 108 (eg, electronic processor 110 in controller 108 ) compares the sample's mass spectrum to reference information to determine whether the sample's mass spectrum represents any known species. The benchmark information may be stored, for example, in storage unit 114 and retrieved by controller 108 to perform analysis. In some embodiments, the controller 108 may also retrieve benchmark information from a database stored at a remote location. For example, controller 108 may communicate with such a database using communication interface 117 to obtain mass spectra of known substances for use in analyzing the information measured by detector 118 .

Information measured by detector 118 is analyzed by controller 108 to determine information about the identity of the sample. If the sample includes multiple compounds, the controller 108 may determine information about the identity of some or all of the multiple compounds by comparing the measured information of the detector 118 with reference information.

Controller 108 is configured to determine various information about the identity of the sample. For example, in certain embodiments, the information includes one or more of the sample common name, IUPAC name, CAS number, UN number, and/or its chemical formula. In certain embodiments, information about the identity of a sample includes information about whether the sample is a class of substance (eg, explosives, energetic materials, fuels, oxidizers, strong acids or bases, toxic substances). In certain embodiments, this information may include information regarding hazards, handling procedures, safety warnings, and reporting procedures associated with the sample. In certain embodiments, this information may include information about the concentration or level of the sample measured by the mass spectrometer.

In some embodiments, the information may include an indication of whether the sample corresponds to the target substance. For example, when the scan begins in step 802, a user of mass spectrometer 100 may place the mass spectrometer in a target mode in which mass spectrometer 100 scans the sample to specifically determine whether the sample corresponds to one of a series of identified target species. any kind. Controller 108 can use various data analysis techniques such as digital filtering and expert systems to search for specific spectral features in the measured mass spectral information. For a particular target substance, the controller 108 may search for a particular mass spectral feature, such as a peak at a particular mass-to-charge ratio, that characterizes the target substance. If the measured mass spectral information lacks a certain spectral feature, or if the measured information includes a spectral feature that should not be present, then the information about the identity of the sample determined by the controller 108 may include that the sample does not correspond to a target substance instructions. Controller 108 may be configured to determine such information for a variety of target compounds.

After the analysis of the sample is complete, the controller 108 uses the display 116 to display information about the sample to the user in step 816 . The displayed information depends on the operating mode of mass spectrometer 100 and user actions. As disclosed in Section I, mass spectrometer 100 is configured such that the mass spectrometer can be used by persons who have no special training in the interpretation of mass spectra. For those without such training, full mass spectra (eg, ion abundance as a function of mass-to-charge ratio) tend to carry less meaning. As a result, mass spectrometer 100 is configured such that in step 816, the measured mass spectrum of the sample is not displayed to the user. Instead, mass spectrometer 100 only displays some (or all) of the information about the identity of the sample determined in step 814 to the user. For the untrained user, information about the identity of the sample is essential.

In addition to information about the identity of the sample, the controller 108 can display other information. For example, in some embodiments, mass spectrometer 100 may have access to a database of known hazardous materials (eg, stored in storage unit 114 , or accessible via communication interface 117 ). If information regarding the identity of the sample exists in the database of hazardous materials, the controller 108 may display an alert message and/or additional information to the user. The warning message may include, for example, information about the relative hazard of the sample. Additional information may include, for example, actions that the user should consider taking, including limiting the exposure of the user or others to the substance, and other safety-related actions.

In certain embodiments, mass spectrometer 100 is configured to display the mass spectrum of the sample to the user when the control is activated. Referring to FIG. 8B , the user interface 112 includes a control 824 that, when activated by the user, displays the mass spectrum of the sample on the display 116 . Control 824 allows a user trained in mass spectrum interpretation to directly view the information measured from detector 118 . This information may be useful, for example, when no definitive match between measured mass spectral information and reference information is obtained. Additionally, when mass spectrometer 100 is used for analysis in a laboratory, for example, a user may activate control 824 in an attempt to deduce more detailed chemical information, such as the fragmentation mechanism of a particular ion. In certain embodiments, mass spectrometer 100 is configured to display the mass spectrum of a sample only when control 824 is activated by the user, and/or after information regarding the identity of the sample has been displayed. That is, mass spectrometer 100 can be configured such that during normal operation, detailed mass spectral information is not displayed to the user; it is only displayed if the user activates control 824 to view this detailed information.

In some embodiments, control 824 may be configured to allow two different modes of operation. For example, when control 824 is activated to a first state by a user of mass spectrometer 100, information regarding the identity of the sample is displayed to the user on display 116 upon completion of the analysis. When control 824 is activated to the second state, mass spectral information (eg, ion abundance as a function of mass-to-charge ratio) is displayed. Accordingly, control 824 may be in the form of a two-way switch that allows the user to select a desired information display mode during operation of the mass spectrometer. In certain embodiments, mass spectrometer 100 may be configured to display information regarding the identity of the sample in addition to mass spectral information when control 824 is activated to the second state.

In step 818, the process shown in flowchart 800 terminates. If the scan was started by the user activating control 820 in step 802, mass spectrometer 100 waits for control 820 to be activated again before starting another scan. Alternatively, if mass spectrometer 100 is in continuous scan mode, mass spectrometer 100 waits for a defined time interval and then automatically starts another scan after the time interval has elapsed, or waits for another external trigger such as a sensor signal.

As previously discussed, generally, mass spectrometer 100 does not use filters that filter atmospheric gas particles. As a result, when analyte particles are introduced into the mass spectrometer, atmospheric gas particles are also introduced, forming a mixture of gas particles in mass spectrometer 100 . Because mass spectrometer 100 operates at higher pressures than the internal pressure in conventional mass spectrometers, and because the components of mass spectrometer 100 are generally insensitive to atmospheric gas particles, the mass spectrometers disclosed herein can be used to Introduce the analyte. Specifically, particles of the analyte may be introduced by continuous inhalation of a mixture of analyte particles and atmospheric gas particles, whereby no particles are filtered. In certain embodiments, mass spectrometer 100 can be configured to pass through sample inlet 124 for at least 10 seconds (e.g., at least 15 seconds, at least 20 seconds, at least 30 seconds, at least 45 seconds for at least 1 minute, at least 1.5 minutes, at least 2 minutes, at least 3 minutes, The mixture of gas particles is continuously introduced into gas path 128 for at least 4 minutes, at least 5 minutes) or longer.

Mass spectrometer 100 can also adjust the duty cycle of ion source 102 when analyte particles are continuously introduced over extended time intervals, such that ion source 102 generates ions over extended time intervals (e.g., during the time period during which analyte particles are introduced). part of the entire time interval). As previously explained, the duty cycle of ion source 102 can generally be adjusted (eg, by adjusting duration 274 in FIG. 21 ) to control the time interval over which ions are generated. In some embodiments, mass spectrometer 100 is configured to adjust the duty cycle of ion source 102 so that ions are discharged from ion source 102 in 10s or longer (e.g., 20s or longer, 30s or longer, 40s or longer, 50s or longer, 1 minute or longer, 1.5 minutes or longer, 2 minutes or longer, 3 minutes or longer, 4 minutes or longer, 5 minutes or longer).

As discussed above, mass spectrometer 100 achieves both compactness and low power operation by eliminating certain high power consumption components typically found in conventional mass spectrometers. Among these components, vacuum pumps - especially turbomolecular pumps - are heavy and consume a lot of power. Mass spectrometer 100 includes no such pumps and, as a result, is both lighter and consumes significantly less power than conventional mass spectrometers.

Through the use of pressure regulation subsystem 120, mass spectrometer 100 operates at a significantly higher internal pressure than in conventional mass spectrometers. In general, at higher pressures, the resolution of mass spectrometers degrades due to various mechanisms, including collision-induced line broadening and ion-neutron charge exchange. Therefore, to obtain the highest possible resolution mass spectra, the internal air pressure in the mass spectrometer should be kept as low as possible.

However, as explained above, when the resolution of the mass spectrometer deteriorates from the best possible value, useful information about the sample, such as information about the identity of the sample, can be obtained by measuring the mass spectrum of the sample and provided to the user. Specifically, even when the mass spectrometer 100 operates at a higher internal gas pressure than conventional mass spectrometers and thus has poorer resolution than conventional mass spectrometers, sufficient accuracy between measured mass spectral information and reference information can still be achieved correspond.

Because mass spectrometer 100 operates at a lower resolution than conventional mass spectrometers, in some embodiments, mass spectrometer 100 can also be configured to adaptively adjust the operation of certain components to further reduce its overall power consumption. The components operate adaptively to either achieve a target resolution of the measured mass spectral information, or to achieve sufficient correspondence between the mass spectral information and reference information of known substances or conditions.

FIG. 8C shows a flowchart 850 including a series of steps for adaptive operation of mass spectrometer 100 to achieve sufficient correspondence between measured mass spectral information and reference information for known substances or conditions. The target resolution may be set by a user of mass spectrometer 100 (eg, through a user-defined setting, or through visual inspection of measured mass spectral information), or automatically by controller 108 . In a first step 852, scanning is started in the same manner as disclosed in step 802 above. Next, in step 854, the sample is introduced into mass spectrometer 100 in the same manner as disclosed in step 804 above. In step 856, the sample particles are ionized to generate ions, as disclosed in step 806 above.

Subsequently, in step 858 , the sample ions generated by ion source 102 are detected using detector 118 . Step 858 may be performed without activating ion trap 104 to trap or selectively eject ions. Instead, in step 858 ions generated by ion source 102 pass directly through end cap electrodes 304 and 306 of ion trap 104 and are incident on detector 118 . Voltage source 106 may be configured to apply a potential to electrodes in ion source 102 and detector 118 to create an electric field between ion source 102 and detector 118 to facilitate transport of ions.

Next, in step 860 , the controller 108 determines whether a threshold ion current is detected by the detector 118 . The threshold ion current may be a user-defined and/or user-adjustable setting of mass spectrometer 100 . Alternatively, the threshold ion current may be determined automatically by mass spectrometer 100 based on, for example, controller 108 measurements of dark current and/or noise in detector 118 . If the threshold current has not been reached, ionization of the sample and detection of sample ions continues in steps 856 and 858 . Alternatively, if the threshold ion current has been reached, the controller 108 activates the ion trap 104 and selectively injects ions into the detector 118 in step 862 . The injected ions are detected by detector 118 and the mass spectral information is analyzed by controller 108 in step 864 in an attempt to determine information about the identity of the sample.

As part of the analysis in step 864, the controller 108 can determine the probability that the measured mass spectral information of the sample is derived from a known substance or condition. In step 866 , controller 108 compares the determined probability to a threshold probability to determine whether analysis of the mass spectral information is limited by the resolution of mass spectrometer 100 . If the probability is greater than the threshold, then controller 108 displays information about the sample (eg, the identity of the sample and/or information about the identity of the sample) using display 116 and the process ends at step 870 .

However, if in step 866 the probability is less than the threshold probability value, then analysis of the mass spectral information may be limited by the resolution of the mass spectrometer 100 . To increase the resolution of mass spectrometer 100 , controller 108 adaptively adjusts the configuration of the mass spectrometer before control returns to step 862 .

Controller 108 is configured to adjust the configuration in various ways to increase the resolution of mass spectrometer 100 . In certain embodiments, controller 108 is configured to activate buffer gas source 150 to introduce buffer gas particles into gas path 128 . The introduced buffer gas particles may comprise, for example, nitrogen molecules, hydrogen molecules or atoms of a noble gas such as helium, neon, argon or krypton. Buffer gas source 150 may comprise a replaceable cylinder containing particles of buffer gas, and a valve connected to controller 108 via control line 127g, or a buffer gas generator. Controller 108 may be configured to activate a valve in buffer gas source 150 such that a controlled amount of buffer gas particles is released into gas path 128 . Once released into gas path 128 , the buffer gas particles mix with ions generated by ion source 102 and facilitate capture and selective ejection of ions into detector 118 , thereby increasing the resolving power of mass spectrometer 100 .

In some embodiments, controller 108 reduces the internal gas pressure in mass spectrometer 100 to increase the resolving power of mass spectrometer 100 . To reduce the internal air pressure, controller 108 activates pressure regulation subsystem 120 via control line 127d. Alternatively or additionally, controller 108 may close valve 129 to reduce the internal air pressure. In some embodiments, valve 129 may be alternately opened and closed in a pulsed manner with a specific duty cycle to reduce internal air pressure. In certain embodiments, mass spectrometer 100 may include multiple sample inlets, and valve 129 may be closed to seal sample inlet 124, while another in-line valve in the smaller diameter sample inlet may be opened. By using a different sample inlet to reduce the air pressure in the mass spectrometer 100, no change in pumping speed is necessary. Reducing the internal gas pressure in mass spectrometer 100 increases the resolution of mass spectrometer 100 by reducing the frequency of collisions between ions in ion source 102 , ion trap 104 , and detector 118 .

In some embodiments, to increase the resolution of mass spectrometer 100 , controller 108 increases the frequency of potential changes applied to center electrode 302 . By reducing the rate of change of the applied potential, the rate of change of the internal electric field within electrode 302 is also reduced. As a result, the selectivity of ion ejection from ion trap 104 is increased, thereby improving the resolution of mass spectrometer 100 .

In certain embodiments, controller 108 is configured to vary the frequency or magnitude of the axial electric field within ion trap 104 to vary the resolution of mass spectrometer 100 . Changing the axial electric field in the ion trap 104 can shift the ejection boundary of the ion trap, thereby extending or reducing the high mass range of the mass spectrometer and changing the resolving power and/or resolution of the mass spectrometer 100 .

In certain embodiments, controller 108 is configured to increase the resolution of mass spectrometer 100 by varying the duty cycle of ion source 102 . It has been observed through experiments that reducing the ionization time can improve the resolution of the mass spectrometer 100 . Thus, referring to graph 270 in FIG. 21 , by reducing the duration 274 of bias potential 272 applied to ion source 102 (eg, reducing the duty cycle of ion source 102 ), the resolution of mass spectrometer 100 may be increased.

Conversely, reducing the resolution of mass spectrometer 100 may also be useful in certain circumstances. For example, referring to graphs 270 and 280 in FIG. 2I, by increasing the duration 274 of bias potential 272 applied to ion source 102 (e.g., increasing the duty cycle of ion source 102), and thus reducing the The resolution of the mass spectrometer 100 is reduced for the duration of the potential amplitude of the electrode 302 of the ion trap 104 (for example, time intervals 284 and 286 in the graph 280), but the sensitivity of the mass spectrometer 100 is increased, thereby increasing The signal-to-noise ratio of the mass spectral information measured using the mass spectrometer 100 . The increased sensitivity is especially useful when trying to detect very low concentrations of certain substances.

In certain embodiments, controller 108 is configured to increase the resolution of mass spectrometer 100 by increasing the duration (e.g., time interval 286 in FIG. 21 ) when increasing the potential applied to electrode 302 of ion trap 104 . By increasing the sweep duration, circulating ions are more slowly ejected from the ion trap 104, thereby increasing the resolution of the measured mass spectral information.

In certain embodiments, controller 108 is configured to vary the resolution of mass spectrometer 100 by adjusting the ramp profile associated with the magnitude sweep of the potential applied to electrode 302 . As shown in graph 280 in FIG. 21 , the magnitude of the potential applied to electrode 302 generally increases according to a linear ramp function. More generally, however, the controller 108 may be configured to increase the magnitude of the potential applied to the electrode 302 according to different ramp profiles. For example, the ramp profile may be adjusted by controller 108 such that the applied potential increases according to a series of different linear ramp profiles, each different ramp profile representing a different rate of increase in potential. As another example, the ramp profile may be adjusted such that the magnitude of the potential applied to the electrode 302 increases according to a non-linear function, such as an exponential or polynomial function.

As discussed above, controller 108 is configured to take any one or more of the actions described above to change the resolution of mass spectrometer 100 . The order in which these actions are taken may be determined by mass spectrometer 100 or by user preference. For example, in some embodiments, a user of mass spectrometer 100 may specify which of the above-described steps, and in what order, controller 108 takes to increase the resolution of mass spectrometer 100 and/or reduce its power consumption. User selections may be stored in storage unit 114 as a set of preferences. Alternatively, in some embodiments, the sequence of actions taken by the controller 108 may be permanently encoded into the logic of the controller 108 or stored in the memory unit 114 as an immutable setting.

In some embodiments, controller 108 may determine the sequence of actions based on other considerations. For example, to ensure that mass spectrometer 100 consumes as little electrical power as possible, the sequence of actions taken by controller 108 to increase the resolving power of mass spectrometer 100 may be determined based on the increase in power consumption as a result of each action. The controller 108 may be provided with information on how each of the actions disclosed above increases overall power consumption, and may select an appropriate sequence of actions based on the power consumption information, with actions resulting in the smallest increase in power consumption appearing first. Alternatively, controller 108 may be configured to measure the increase in power consumption associated with each action, and may select an appropriate sequence of actions based on the measured power consumption values.

Although in the flowchart 850, the adjustment of the configuration of the mass spectrometer 100 is based on the probability that the measured mass spectral information corresponds to the known reference information, the adjustment of the configuration of the mass spectrometer 100 can also be based on other criteria. In some embodiments, for example, adjustments to the configuration of mass spectrometer 100 may be made based on whether a target resolution for mass spectrometer 100 has been achieved. In step 864, the controller 108 determines the actual resolution of the mass spectrometer 100 based on the measured mass spectrum information (eg, based on the maximum FWHM of the single ion peak within the measurement window of the mass spectrometer 100). In step 866 , the actual resolution is compared by controller 108 to the target resolution of mass spectrometer 100 . If the actual resolution is less than the target resolution, then, in step 872, the controller 108 adjusts the configuration of the mass spectrometer 100 to increase the resolution of the mass spectrometer as discussed above.

Hardware, Software and Electronic Processing

Any method steps, features, and/or attributes disclosed herein may be performed by controller 108 (e.g., electronic processor 110 of controller 108) and/or one or more additional electronic processors executing programs based on standard programming techniques (such as computer or preprogrammed integrated circuit). Such programs are designed to be executed on programmable computing devices or specially designed integrated circuits, each device including a processor, a data storage system (including memory and/or storage elements), at least one storage device, and at least one display device , such as a monitor or printer. Program code is applied to input data to perform functions and generate output information that is applied to one or more output devices. Each such computer program may be implemented in a high-level procedural or object-oriented programming language or assembly or machine language. Also, a language can be a compiled or interpreted language. Each such computer program can be stored on a computer-readable storage medium (e.g., CD-ROM or magnetic disk), which, when read by a computer, can cause a processor in the computer to perform analysis and control the functions described herein .

other embodiments

In certain embodiments, mass spectrometer 100 is configured to operate at higher gas pressures, such as up to 1 atm (eg, 760 Torr). That is, when mass spectrometer 100 detects ions based on their mass-to-charge ratio, the internal gas pressure in one or more of ion source 102, ion trap 104, and/or detector 118 is between 100 Torr and 760 Torr (e.g., 200Torr or more, 300Torr or more, 400Torr or more, 500Torr or more, 600Torr or more).

Certain components disclosed herein are also suitable for operation at pressures up to 1 atm (and even higher pressures). For example, certain ion sources disclosed herein, such as glow discharge ion sources, can be operated at pressures up to 1 atm with little or no modification. In addition, certain types of detectors such as Faraday detectors (eg Faraday cup detectors and arrays thereof) can also be operated at pressures up to 1 atm with little or no modification.

The ion traps disclosed herein can be modified to operate at pressures up to 1 atm. For example, referring to FIG. 3A , to operate at a pressure of 1 atm, the size c of the ion trap 104 should be reduced to between 1.5 microns and _0.5 microns (e.g., between 1.5 microns and 0.7 microns, between 1.2 microns and 0.5 microns Between, between 1.2 microns and 0.8 microns, approximately 1 micron). In addition, for operation at gas pressures up to 1 atm, voltage source 106 can be modified to provide a sweep voltage to ion trap 104 at a frequency of GHz, such as 1.0 GHz or higher (e.g., 1.2 GHz or higher, 1.4 GHz or higher, 1.6GHz or higher, 2.0GHz or higher, 5.0GHz or higher or even higher). With these modifications to ion trap 104 and voltage source 106 , mass spectrometer 100 can operate at pressures up to 1 atm, resulting in significantly less use of pressure regulation subsystem 120 . In certain embodiments, it is even possible to remove pressure regulation subsystem 120 from mass spectrometer 100 such that, for example, mass spectrometer 100 is a pumpless mass spectrometer.

Several embodiments have been described. It should be understood, however, that various changes may be made without departing from the spirit and scope of the present disclosure. Accordingly, other embodiments are within the scope of the following claims.

Claims (10)

1. a kind of mass spectrograph, it includes：

Ion gun；

Ion trap；

Ion detector；And

Pressure regulation system,

Wherein, during the mass spectrograph is run：

The pressure regulation system is configured as at least two in the ion gun, the ion trap and the ion detector The air pressure between 100mTorr and 100Torr is maintained in a；And

The ion detector is configured as detecting the ion according to the mass-to-charge ratio of the ion generated by the ion gun.

2. mass spectrograph according to claim 1, wherein, during operation, the pressure regulation system is configured as in institute State the air pressure maintained in ion trap and the ion detector between 100mTorr and 100Torr.

3. mass spectrograph according to claim 1, wherein, during operation, the pressure regulation system is configured as in institute State the air pressure maintained in ion gun and the ion trap between 100mTorr and 100Torr.

4. mass spectrograph according to claim 1, wherein, during operation, the pressure regulation system is configured as in institute State the air pressure maintained in ion gun and the ion detector between 100mTorr and 100Torr.

5. mass spectrograph according to claim 1, wherein, during operation, the pressure regulation system is configured as in institute State the air pressure maintained in ion gun, the ion trap and the ion detector between 100mTorr and 100Torr.

6. mass spectrograph according to claim 1, wherein, the ion gun includes glow discharge ionization source.

7. mass spectrograph according to claim 1, wherein, the pressure regulation system includes air pump, and the air pump is configured Air pressure in described at least two in the ion gun, the ion trap and the ion detector in order to control.

8. mass spectrograph according to claim 7, further include controller, the controller be configured as activating the air pump with Control the air pressure in described at least two in the ion gun, the ion trap and the ion detector.

9. mass spectrograph according to claim 7, wherein, the air pump includes vortex pump.

10. mass spectrograph according to claim 1, wherein, during operation, the pressure regulation system is configured as in institute Maintained in stating described at least two in ion gun, the ion trap and the ion detector 500mTorr and 10Torr it Between air pressure.