JP2008282571A - Time-of-flight mass spectrometer - Google Patents

Abstract

A time-of-flight mass spectrometer having high mass resolution and capable of measuring with high quantitativeness is provided.
An ion source for generating a plurality of ions to be analyzed and accelerating in a pulse manner, an ion flying unit for flying a plurality of ions supplied from the ion source, and a mass charge in the ion flying unit. A deflector 16 that deflects a plurality of ions separated by a time-of-flight difference corresponding to a ratio in a plurality of directions, and a first detector that is provided in a first direction among the plurality of directions and detects a part of the plurality of ions 18a, and a second detector 18b that is provided in a second direction among the plurality of directions and detects other part of the plurality of ions with a wider dynamic range than the first detector 18a.
[Selection] Figure 1

Description

  The present invention relates to a time-of-flight mass spectrometer.

  In mass spectrometry, ions to be analyzed are separated and detected according to the mass-to-charge ratio using a mass spectrometer. Elemental analysis is performed from the mass spectrum of the detected ions.

  For example, a mass analyzer is used for measuring the isotope abundance ratio and element abundance of the analysis target. When the mass resolution of the mass analyzer is low, the ions to be analyzed are distinguished from each other by confirming the isotope pattern for a substance having a minute mass difference from the analysis object.

  When measuring isotope abundance ratio, element abundance, etc. using a mass analyzer with high mass resolution, there are problems in detection sensitivity and quantitativeness. For example, as a high mass resolution mass spectrometer, a Fourier transform ion cyclotron resonance type (FT) mass spectrometer, a time-of-flight type (TOF) mass spectrometer, and the like can be given. The FT mass spectrometer has poor detection sensitivity, and the TOF mass spectrometer has a narrow range of quantitativeness. Therefore, it is difficult for these high mass resolution mass spectrometers to measure the isotope abundance ratio and element abundance accurately and quantitatively.

For various analytical purposes such as high-sensitivity microanalysis and analysis that requires high mass resolution, there are those in which a plurality of mass spectrometers suitable for each analytical purpose are arranged (for example, see Patent Document 1). ). However, since a plurality of mass spectrometers are arranged, the apparatus becomes large and the apparatus cost increases, which is not desirable.
JP 2002-184347 A

  A mass spectrometer used for measurement of isotope abundance ratio, element abundance, and the like is required to be quantitative. Therefore, it is desirable to use a detector such as an electron multiplier or a Faraday cup that has a wide output dynamic range and good linearity. However, such a detector has a slow reaction time, and is not suitable as a detector for a TOF mass spectrometer that requires high speed, for example.

  Even if there is a detector having a wide dynamic range and a fast reaction time, the detector is limited by the dynamic range of a high-speed signal processing circuit that processes the output signal of the detector. As a result, it was difficult to measure the abundance of elements over a wide range with a good quantitativeness using a TOF mass spectrometer.

  In view of the above problems, an object of the present invention is to provide a TOF mass spectrometer having high mass resolution and capable of measuring with high quantitativeness.

  In order to achieve the above object, according to an aspect of the present invention, (a) an ion source that generates a plurality of ions to be analyzed and accelerates them in a pulsed manner, and (b) a plurality of ions supplied from the ion source fly. An ion flight unit, (c) a deflector that deflects a plurality of ions separated by a time-of-flight difference corresponding to a mass-to-charge ratio in a plurality of directions, and (d) a first direction in the plurality of directions. A first detector for detecting a part of a plurality of ions; and (e) a plurality of ions provided in a second direction among a plurality of directions and having a wider dynamic range than the first detector. The gist of the invention is that it is a time-of-flight mass spectrometer provided with a second detector that detects a part of the second detector.

  According to the present invention, it is possible to provide a TOF mass spectrometer having high mass resolution and capable of measuring with high quantitativeness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the configuration of the apparatus and system is different from the actual one. Therefore, a specific configuration should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different structures and the like are included between the drawings.

  The following embodiments of the present invention exemplify apparatuses and methods for embodying the technical idea of the present invention. The technical idea of the present invention is based on the material and shape of component parts. The structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

  As shown in FIG. 1, the TOF mass spectrometer according to the embodiment of the present invention includes an ion source 10, an ion flight unit 12, an ion discriminator 14, a deflector 16, a first detector 18a, and a second detector 18b. , A first signal processing circuit 20a, a second signal processing circuit 20b, and the like.

  The ion source 10 generates ions to be analyzed. The generated ions are accelerated in a pulse manner by the extraction voltage of the ion source 10 and supplied to the ion flying unit 12.

  The ion flying unit 12 flies the supplied ions. The ions are separated by the time-of-flight difference corresponding to the mass-to-charge ratio while flying through the ion flying unit 12.

  The ion discriminator 14 discriminates target ions from ions flying in the ion flying unit 12. Excluded ions are excluded from the ion flight unit 12. As the ion discriminator 14, a deflector, a lens, and the like are installed on the flight trajectory of the ion flight unit 12.

  The deflector 16 deflects the ions separated by the ion flying unit 12 in a plurality of directions. For example, the ions are deflected in the first and second directions by an electric field or a magnetic field.

  The first and second detectors 18a and 18b sensitize and detect ions deflected in the first and second directions, respectively.

  The first and second signal processing circuits 20a and 20b create mass spectra based on the time of flight of ions detected by the first and second detectors 18a and 18b, respectively.

  As the first detector 18a, a high-speed detector having a high time resolution such as a microchannel plate (MCP) is used as in a normal TOF mass spectrometer. In general, high-speed detectors such as MCP have a relatively narrow dynamic range. Further, as the first signal processing circuit 20a, a high-speed signal processing circuit is used even if the dynamic range is narrow according to the first detector 18a.

  As the second detector 18b, a quantitative detector having a wide dynamic range such as an electron multiplier, a photomultiplier, or a Faraday cup is used. Further, as the second signal processing circuit 20b, a processing circuit having a wide dynamic range is used even if the processing speed is low according to the second detector 18b.

  For example, in the case of performing qualitative analysis by separating ions with high mass resolution with respect to the analysis target, the first detector 18a having high time resolution is used. In the ion flight part 12, all the ions to be analyzed can be separated. The first detector 18a has high time resolution, can perform qualitative analysis of separated ions, and can perform mass analysis with high mass resolution. However, the first detector 18a and the first signal processing circuit 20a have a narrow dynamic range and are not suitable for quantitative analysis.

  In quantitative analysis of ions to be analyzed, ions are deflected by the deflector 16 so that the ions reach the second detector 18b having a wide dynamic range. In this case, ions other than the target are excluded by the ion discriminator 14 so that the target ions, which are separated and confirmed by the first detector 18a in advance, are selectively detected by the second detector 18b. The ions detected by the second signal processing circuit 20b can be measured with good quantitativeness.

  As described above, in the TOF mass spectrometer according to the embodiment of the present invention, the second detector 18b having a wide dynamic range is installed in addition to the high-speed first detector 18a used in the normal TOF mass spectrometer. Has been. The ions flying through the ion flying unit 12 are deflected by the deflector 16 and reach one of the first and second detectors 18a and 18b. Based on the mass spectrum obtained qualitatively using the first detector 18a, ions of interest can be selectively detected using the second detector 18b. As a result, it is possible to measure the isotope abundance ratio and element abundance of the target ion with high mass resolution and high quantitativeness.

  The second detector 18b and the second signal processing circuit 20b are low speed. Therefore, in the measurement of the isotope abundance ratio, when the time difference of flight of the isotope ions reaching the second detector 18b and the second signal processing circuit 20b is short, it is difficult to measure them separately. In such a case, each of the isotope ions may be individually supplied to the second detector 18b by the deflector 16 and measured.

  Alternatively, as shown in FIG. 2, the third detector 18c and the third signal processing circuit 20c having a wide dynamic range capable of quantitative measurement may be installed in the TOF mass spectrometer. The deflector 16 deflects the second and third detectors 18b and 18c so as to be sequentially distributed within the time-of-flight difference between the isotope ions. In this way, it is possible to measure each of the isotope ions having a short time-of-flight difference with good quantitativeness.

  Moreover, as shown in FIG. 3, the structure which abbreviate | omitted the ion discriminator may be sufficient. In this case, ions are discriminated by the deflector 16. The deflector 16 deflects ions by an electric field, a magnetic field, and a combination of an electric field and a magnetic field, and spatially distributes the ions to the first and second detectors 18a and 18b. That is, by changing the electric field or magnetic field, the ions temporally separated by the ion flying unit 12 can be spatially separated by the deflector 16.

  For example, the target ion is determined using the first detector 18a. Next, by adjusting the deflector 16, the target ions are selectively made to reach the second detector 18b. In this way, ion discrimination can be performed by the deflector 16.

(Other embodiments)
As mentioned above, although this invention was described by embodiment of this invention, it should not be understood that the statement and drawing which make a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is the schematic which shows an example of a structure of the time-of-flight mass spectrometer which concerns on embodiment of this invention. It is the schematic which shows the other example of a structure of the time-of-flight mass spectrometer which concerns on embodiment of this invention. It is the schematic which shows the further another example of a structure of the time-of-flight mass spectrometer which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Ion source 12 ... Ion flight part 14 ... Ion discriminator 16 ... Deflector 18a ... 1st detector 18b ... 2nd detector 18c ... 3rd detector 20a ... 1st signal processing circuit 20b ... 2nd signal processing circuit 20c ... Third signal processing circuit

Claims (4)

An ion source that generates a plurality of ions to be analyzed and accelerates them in pulses,
An ion flying section for flying a plurality of ions supplied from the ion source;
A deflector for deflecting the plurality of ions separated by a time-of-flight difference corresponding to a mass-to-charge ratio in a plurality of directions in the ion flight unit;
A first detector provided in a first direction among the plurality of directions and detecting a part of the plurality of ions;
A second detector provided in a second direction of the plurality of directions and detecting another part of the plurality of ions with a wider dynamic range than the first detector. Time-type mass spectrometer.
A third detector provided in a third direction among the plurality of directions and further detecting another part of the plurality of ions with a wider dynamic range than the first detector. The time-of-flight mass spectrometer according to claim 1.
The time-of-flight mass spectrometer according to claim 1 or 2, further comprising an ion discriminator that discriminates target ions from the plurality of ions in the ion flight unit.
  The time-of-flight mass spectrometer according to claim 1, wherein the deflector discriminates a target ion from the plurality of ions.

Images