GB2633330A

GB2633330A - Detection system and vapour storage module

Info

Publication number: GB2633330A
Application number: GB2313521.3A
Authority: GB
Inventors: Swallow Philip; Brian Wheatley Alan
Original assignee: Smiths Detection Watford Ltd
Current assignee: Smiths Detection Watford Ltd
Priority date: 2023-09-05
Filing date: 2023-09-05
Publication date: 2025-03-12
Also published as: WO2025052104A1; GB202313521D0

Abstract

A removable vapour storage module 102 is disclosed that enables replacement and/or servicing of the module to be performed while a detection system 100, e.g. a mass or ion mobility spectrometer, remains in use. The vapor storage module comprises: a flow passage 106 separated from a chamber 104 storing a source of vapour 105 by a valve 110, the flow passage being configured to receive a carrier gas flow from, and provide an outlet flow to, the detection apparatus 202; and absorbent material 114 & 118 in fluid communication with the flow passage for inhibiting diffusion of vapour into the detection apparatus. The vapour storage module is designed to detachably couple to the detection apparatus via a first interface portion comprising a first connector 124 at an inlet 107 of the flow passage and a second connector 122 at the outlet 108, the detection apparatus comprising a second interface portion configured to couple with the first to provide a sealed connection therewith.

Description

Detection system and vapour storage module The present disclosure relates to detection systems and vapour storage modules for detection systems, and more particularly to detection systems comprising removable vapour storage modules, still more particularly to vapour storage modules containing absorbent materials for inhibiting diffusion of vapour into a detection apparatus and methods of servicing a vapour generator of a detection system. These methods and apparatus may find particular application in spectrometry, for example ion mobility spectrometry and mass spectrometry.

In ion mobility spectrometers, and other detection systems which sample vapours, it may be useful to provide a calibrant, a dopant, or other vapour into the spectrometer. Calibrant may for example be dosed into a detection system manually using an external source of vaporised calibrant. However, this requires external vapour sources to be carried for the purpose of calibration and precludes automatic calibration cycles instigated by the detection system, which may be disadvantageous when the detection system is intended for use by a user who may not have technical expertise.

A detection system may in some cases contain an internal source of vapour, such as a calibrant, and a system for delivering the calibrant into the detector. However, this presents challenges when it comes to servicing as the entire detection system must be taken out of action in order to service the unit, and may for example need to be provided to a remote location for servicing by those with the relevant technical expertise.

Calibrant samples can in some instances leak from internal sources of vapour within a detection apparatus and interfere with its operation.

Summary

Embodiments of the disclosure relate to detection systems and removable vapour storage modules and vapour generators for detection systems, as well methods of servicing a vapour generator of a detection system. -2 -

Detectors such as ion mobility spectrometers or mass spectrometers may be configured to receive a calibrant vapour for calibrating the detector (or in some cases a dopant). Such detectors may also contain internally to the detector a source of the vapour, e.g. the calibrant, so that it can be provided on demand, for example to perform calibration automatically in response to user prompt, set time intervals or changing environmental conditions.

In such systems it is desirable to prevent leakage of such vapours from a source of vapour within the detector, as such leaks can interfere with normal operation of the detector. A detector may contain absorbent materials configured to absorb vapour that leaks from the vapour source to inhibit undesired passage of the vapour from the vapour source into the detector.

Calibrants used in such systems may comprise volatile calibrant samples having high vapour pressure, for example a calibrant such as isofluorane. This presents problems as such samples are harder to contain because the high vapour pressure leads to increased diffusion of the vapour from the vapour source into the detector. This can also present problems with absorbent materials in the detector as increased leakage of the vapour may lead to the need to service detectors to replace absorbent materials, as well as the vapour source emptying faster due to increased evaporation of the calibrant from the vapour/calibrant source.

Embodiments of the disclosure aim to address such problems by providing a removable vapour storage module that enables servicing of the module to be performed whilst a detection system can be continuously in use by replacing the removed vapour storage module with a new or previously serviced module. In addition, the disclosure aims to address problems with leakage of high vapour pressure calibrants from a vapour store into a connected detection apparatus.

Aspects of the disclosure are set out in the independent claims and optional features are set out in the dependent claims. Aspects of the disclosure may be provided in conjunction with each other, and features of one aspect may be applied to other aspects. -3 -

In an aspect there is provided a detection system comprising: a detection apparatus; and a vapour storage module configured to store vapour for delivery to the detection apparatus, the vapour storage module comprising: a vapour chamber configured to store a source of vapour for delivery to the detection apparatus; a flow passage comprising an inlet configured to receive a carrier gas flow from the detection apparatus and an outlet configured to provide an outlet flow to the detection apparatus, the flow passage separated from the vapour chamber by a valve configured to control the passage of vapour from the vapour source into the flow passage; an absorbent material in fluid communication with the flow passage configured to inhibit diffusion of vapour in the flow passage into the detection apparatus; and a housing containing the vapour chamber, the flow passage and the absorbent material, the housing comprising a first interface portion comprising a first connector at the inlet of the flow passage and a second connector at the outlet of the flow passage; wherein the vapour storage module is removably coupled to the detection apparatus, the detection apparatus comprising a second interface portion configured to couple with the first interface portion of the vapour storage module, the first and second interface portions configured to align the first connector with a flow outlet of the detection apparatus to provide a sealed connection, and to align the second connector with a vapour inlet of the detection apparatus to provide a sealed connection.

A detection system comprising a removable vapour storage module according to the present disclosure can have the benefit that the module may be removed, for example for servicing, and replaced with a new or previously serviced module. The vapour storage module not only contains a vapour store that may be refilled during servicing, but also contains absorbent material to inhibit leakage of the vapour from the vapour storage module, and the absorbent material can advantageously also be renewed (for example by treating it to remove previously absorbed materials) or replaced. In this way, the vapour storage module may be replaced whilst only requiring a short period of time in which the detection system is unusable. In contrast, without a removable vapour storage module as described herein, the entire detection system may need to be sent for servicing and be unusable for that entire time period. This may be particularly advantageous where the detection system is used in a remote location, for example where the detection system comprises a portable or handheld detection system, and on-site servicing at the point of use of the detection system is difficult. -4 -

As discussed, the vapour storage module is removably coupled to the detection apparatus. The coupling between the vapour storage module and the detection apparatus may be provided in any suitable way so as to permit the vapour storage module to, when coupled, provide vapour from the vapour chamber along the flow path via the outlet to the vapour inlet of the detection apparatus. The system is also configured so that the vapour storage module can be entirely decoupled from the detection apparatus so that the vapour storage module can be sent for servicing separately to the detection apparatus, for example so that the vapour storage module can be replaced with a different vapour storage module.

The detection apparatus comprises a second interface portion configured to couple with the first interface portion of the vapour storage module, in order to align the vapour storage module with the detection apparatus. The form of the first and second interface portions may correspond to guide and hold the first and second interface portions in the correct position (for example to provide a form fit connection between the vapour storage module and the detection apparatus).

The first and second interface portions may comprise one or more locking elements configured to hold the vapour storage module coupled to the detection apparatus, where the locking element is releasable to remove the vapour storage apparatus. A locking element may for example comprise one or more clips or screws configured to hold the vapour storage module in the coupled position with the detection apparatus. In some embodiments, the vapour storage module is configured to remain attached to the detection apparatus by friction, for example by an interference fit.

The first and second interface portions may be configured so that the vapour storage module and the detection apparatus can only be coupled in one orientation. In this way, incorrect coupling of the vapour storage module and the detection apparatus may be avoided. Alternatively, the first and second interface portions may be configured to couple the vapour storage module with the detection apparatus in two different orientations. For example, the vapour storage module may be symmetrical in respect of the flow passage from the inlet to the outlet, for example wherein the inlet and the outlet are equivalent when the vapour storage module is not coupled to the detection -5 -apparatus, and the first and second interface portions are configured to permit the vapour storage module to be coupled to the detection apparatus in either of two equivalent orientations.

The second interface portion of the detection apparatus may comprise a recess in an external wall of the detection apparatus, where the recess is configured to receive the vapour storage module. The second interface portion may comprise one or more guiding elements such as ridges or grooves configured to guide the vapour storage module into the coupled position, which may cooperate with one or more corresponding guiding elements of the first interface portion. Similarly, the first interface of the vapour storage module may comprise one or more guiding elements configured to align the vapour storage module for coupling with a detection apparatus, for example to cooperate with one or more corresponding guiding elements of the detection apparatus.

The vapour storage module comprises a housing that contains the vapour chamber, the flow passage and the absorbent material. As will be appreciated, the vapour chamber, the flow passage and the absorbent material may be contained by the housing in the sense that they are held in position relative to each other by the housing (but may nonetheless extend partially outside the housing. The housing may in embodiments completely enclose the vapour chamber, the flow passage and the absorbent material so that the only entrance into the interior of the housing is provided by the inlet and the outlet of the flow passage.

The housing comprises the first interface portion configured to couple to a second interface portion of the detection apparatus. The first interface portion comprises a first connector at the inlet of the flow passage and a second connector at the outlet of the flow passage. The first and second connectors may comprise any connectors suitable for providing a sealed coupling with the flow outlet and the vapour inlet of the detection apparatus. For example, the first and/or the second connector may comprise the plug portion of a plug and socket connection, for example comprising a tubular protrusion that extends from the housing of the vapour storage module for coupling with the detection apparatus. In this case, the detection apparatus at the flow outlet or vapour inlet may comprise a corresponding socket portion of a plug and socket connection configured to -6 -receive the plug portion from the vapour storage module. The first and second connector may both comprise a plug portion or may both comprise a socket portion, configured to couple with corresponding plug or socket portions of the detection apparatus. Alternatively, the first and second connectors may not be equivalent, for example the first connector may comprise a comprise a plug connection and the second connector may comprise a socket connection, or vice versa (which may suitably restrict the orientation in which the vapour storage module and the vapour storage module can be coupled). Similarly, the second interface portion of the detection apparatus may comprise a third connector at the flow outlet configured to provide a sealed connection with the first connector of the vapour storage module and a fourth connector at the vapour inlet configured to provide a sealed connection with the second connector of the vapour storage module.

The first interface portion of the vapour storage module and the second interface portion of the vapour storage module may comprise a first electrical coupling and a second electrical coupling, respectively, wherein the first and second electrical couplings are configured to mate when the vapour storage module is coupled to the detection apparatus to provide electronic communications between the vapour storage module and the detection apparatus. For example, the electrical couplings may facilitate electronic communication between the vapour storage module and a controller configured to control operation of the detection system.

The detection apparatus may comprise any suitable analyser for detecting a substance of interest. The detection apparatus may comprise at least one of an ion mobility spectrometer (IMS), a differential mobility spectrometer (DMS), a mass spectrometer (MS), a chromatography apparatus (for example a gas chromatography system) and an optical spectrometer (for example an infrared spectrometer or a Raman spectrometer). In embodiments, the detection apparatus may comprise an ion mobility spectrometer, a mass spectrometer, or a combined IMS-MS. An IMS may comprise a positive IMS and/or a negative mode IMS. In embodiments the detection apparatus comprises both a positive mode IMS and a negative mode IMS. In some embodiments a single IMS may be switchable between positive and negative modes and may be configured to rapidly switch between positive and negative modes in order to analyse a single sample in both -7 -the positive and negative modes. The detection apparatus preferably comprises an ion mobility spectrometer (IMS).

The detection apparatus may be portable, for example a handheld detector, and may comprise a portable power source that can be carried by the detector. A portable power source may comprise a battery, a fuel cell, a capacitor, or any other portable source of electrical power suitable for providing electrical power to the detector. The detection apparatus may suitably be configured to draw the flow of air to be tested into the detection apparatus from an ambient environment in which it is situated. For example, the detection apparatus may be configured to detect substances of interest in the air of the ambient environment in which the detector is operated (rather than drawing a flow to be sampled from another apparatus such as a chromatography apparatus or a pre-collected sample). For example, the detection apparatus may comprise a housing configured to contain the detection system, wherein the detection apparatus is configured to draw the flow of air to be tested from the air of the ambient environment outside of the housing.

The vapour inlet of the detection apparatus may be configured to provide vapour from the flow passage to the detection apparatus for calibrating the detection apparatus. Thus, in preferred embodiments the vapour to be provided to the detection apparatus is a calibrant. Where the detection apparatus comprises an ion detection apparatus, for example an ion mobility spectrometer, a mass spectrometer, or a combination thereof, the vapour inlet of the detection apparatus may suitably be configured to provide vapour received from the flow passage to an ionisation region of the detection apparatus. For example, in an ion mobility spectrometer, the vapour inlet of the detection apparatus may suitably be configured to provide vapour received from the flow passage to a reaction region of the ion mobility spectrometer for ionisation. As will be appreciated, in general an ion mobility spectrometer may comprise a reaction region in which a sample is ionised, and a drift region that separates the reaction region from a detector (for example a Faraday plate or in an IMS-MS system, a mass spectrometer), where the spectrometer is configured to characterise ions based on their time of flight from a gate (or in some instances an ion trap) separating the reaction region from the drift region to the detector. A flow of drift gas is provided in an opposing direction to the direction of travel of the ions -8 -in the drift region, so that the ions travel against a flow of drift gas.

The vapour from the vapour inlet of the detection apparatus may be provided directly to an ionisation region of the detection apparatus, or may be provided to the ionisation region indirectly, for example to an inlet from which samples are provided to the ionisation region by the detection apparatus, for example an inlet configured to, in normal operation, receive a flow of air to be tested that is drawn into the ionisation region. In this way, the calibrant can be ionised and analysed by the detection apparatus for the purpose of calibration. Preferably, the vapour from the vapour inlet of the detection apparatus may be provided directly to an ionisation region of the detection apparatus. As will be appreciated, operation of the detection apparatus to ionise and analyse vapour from the vapour chamber may suitably be synchronised with operation of the valve of the vapour storage module and one or more flow providers to provide a flow of vapour (e.g. calibrant) from the vapour chamber, via the flow passage, to the vapour inlet and to the detection apparatus (e.g. to an ionisation region as described).

The detection system may suitably comprise a flow provider configured to provide a flow of carrier gas to the inlet of the flow passage, past the valve and through the outlet of the flow passage to the vapour inlet, wherein when the valve is open, vapour exiting the vapour source is carried by the carrier gas to the detection apparatus through vapour inlet. As will be appreciated, the detection system may be controlled to synchronise operation of the flow provider with opening of the valve to provide a flow of vapour from the vapour chamber along the flow passage to the outlet and into the vapour inlet of the detection apparatus. Operation of the flow provider and opening of the valve may also be synchronised with operation of the detection apparatus, for example to perform calibration of the detection apparatus using a calibrant from the vapour chamber. The flow provider may suitably be arranged in the detection apparatus so that flow through the flow passage of the vapour storage module is provided by positive pressure at the flow outlet of the detection apparatus and/or a negative pressure at the vapour inlet of the detection apparatus to drive flow from the inlet to the outlet of the flow passage.

A flow provider as referred to herein may in general be provided by any suitable device, for example a pump, a fan or any other suitable device for providing a flow of air through -9 -the system. The flow provider may comprise a single flow provider device or a combination of more than one flow provider device, for example the flow provider may comprise one or more pumps or fans.

Where the detection apparatus provides a carrier gas flow from the flow outlet to drive flow along the flow passage from the inlet to the outlet and to the vapour inlet, the source of gas used to provide the carrier gas flow may come from any suitable source. For example, in some instances the detection apparatus is configured to provide the carrier gas flow from a source of gas within the detection apparatus, for example the carrier gas may comprise a portion of a gas that is circulated within the detection apparatus in normal use (e.g. drift gas in the case of an ion mobility spectrometer, where a portion of the drift gas is circulated from the detection apparatus to the flow outlet, through the flow passage to the vapour inlet. Where the carrier gas comprises a portion of the drift gas, the flow of vapour from the vapour inlet is preferably provided directly to the ionisation region. Alternatively, or additionally, the carrier gas may be drawn from an ambient environment in which the detection system is operated, though in this case it will be appreciated that the gas will suitably be purified prior to entering the flow passage, for example via one or more filters, molecular sieves or similar means, so that a clean gas flow enters the flow passage to carry vapour from the vapour chamber to the vapour inlet. Where the carrier gas comprises air drawn from outside the detection apparatus, the vapour flow from the vapour inlet is preferably passed to an inlet of the detection apparatus that is configured to receive a flow of air to be sampled in normal operation, and then sampled by the detection apparatus into the ionisation region.

The valve of the vapour chamber may comprise any suitable valve. In embodiments, the valve is a solenoid valve. For example, the valve may suitable be a solenoid valve comprising an energised seal configured to maintain the valve in a closed configuration when the solenoid valve is not powered. In this way, leakage of vapour from the vapour chamber may be prevented without requiring the valve to be powered. This can be advantageous particularly in the case of a portable detection device having a portable power supply such as a battery, as the power consumed by the valve can be limited to the short periods in which the valve is opened. The energised seal may comprise any suitable energised seal arrangement, for example the valve may comprise a spring or -10 -other biasing member configured to hold the valve in a closed position, wherein the solenoid is operable to act against the biasing member to open the valve.

The valve may comprise a shaft and one or more radial and/or face seals configured to prevent vapour from exiting the vapour chamber when the valve is closed. The shaft suitably comprises an elongate element, and may have any suitable cross section, for example the shaft may comprise a substantially cylindrical shaft. The shaft may extend through the flow passage in order to seal an entrance orifice of the vapour chamber that separates the vapour chamber from the flow passage. Therefore, the valve may comprise one or more radial and/or face seals as environmental seals to prevent leakage of gas and vapour inside the flow passage into the environment (or into the detection apparatus), and to prevent leakage of external gas or vapours into the flow passage past the shaft. The one or more radial and/or face seals may comprise any suitable material, for example the one or more radial and/or face seals may comprise polytetrafluoroethylene (PTFE) seals.

In embodiments, the valve comprises one or more radial seals surrounding the shaft, and the shaft comprises a neck portion in which the cross section (for example the diameter) of the shaft is reduced relative to a portion of the shaft that abuts the radial seals when the valve is closed, so that when the valve is open, the neck portion aligns with the one or more radial seals to permit passage of vapour through the valve into the flow passage.

The valve suitably comprises an enclosure having a passage or bore through which the shaft can move axially to open and close the valve. As will be appreciated, the enclosure may be formed by a material providing the structure of the vapour storage module, for example the housing. The shaft may therefore move axially within a passage or bore through the housing, wherein the shaft may pass through the flow passage into the vapour storage chamber (for example into an orifice connecting the flow passage to the vapour chamber). The shaft is preferably formed from a material that is harder than the material from which the enclosure or housing is formed, for example, wherein the shaft is made from steel, for example stainless steel, and the enclosure is made from plastic, for example PEEK. In this way, scratches on the shaft that may compromise the seal may be avoided. Particularly in the context of sensitive trace detection systems and when using highly volatile calibrants, avoiding leakage of vapour from the vapour chamber in this way is of importance.

The shaft of the valve may have a first end on which the solenoid acts to move the shaft axially (i.e. along an axis parallel to the length of the shaft), and a second end that enters an entrance or orifice of the vapour chamber (that separates the vapour chamber from the flow passage) to seal the vapour chamber.

The second end can comprise a flange portion that extends radially from around the second end of the shaft within the vapour chamber, for example to provide an upper surface of the flange portion that opposes an upper internal wall of the vapour chamber. The valve may be configured so that the flange portion forms a face seal against the upper internal wall of the vapour chamber when the valve is closed (for example by action of the energised seal -e.g. where the biasing member is configured to pull the flange portion towards the upper wall of the vapour chamber). A face seal may be arranged between the flange portion and the upper wall of the vapour chamber to provide a seal to prevent vapour exiting the vapour chamber. Where a flange portion is provided at the second end of the shaft within the vapour chamber, the flange portion may also serve to aid dosing of vapour in the headspace of the vapour chamber into the flow passage. For example, when the valve is open, the flange portion of the shaft is pushed into the vapour chamber to provide a spacing between the upper surface of the flange portion and the face seal/upper wall of the vapour chamber. The spacing between the upper surface of the flange portion and the face seal/upper wall may then fill with vapour from the headspace of the vapour chamber so that when the valve is closed (i.e. when the flange portion is moved towards the face seal/upper wall of the vapour chamber) the flange portion pulls vapour in the spacing towards the exit of the vapour chamber and towards the flow passage. Thus, in addition to providing a face seal to prevent leakage from the vapour chamber, the flange portion of the shaft can also aid in providing more reliable dosing of vapour from the vapour chamber into the flow passage.

Vapour from the vapour chamber may have sufficient vapour pressure so as to diffuse from the vapour chamber into the flow passage through the valve simply by opening the valve. Nonetheless, it will be appreciated that in some embodiments, the vapour -12 -chamber may comprise means for increasing the pressure of the vapour within the vapour chamber to urge vapour from the vapour chamber into the flow passage when the valve is open. For example, the vapour chamber may comprise a heater. Preferably, the vapour storage module is configured so that vapour from the vapour chamber passes from the vapour chamber into the flow passage by diffusion at ambient temperature by virtue of only the vapour pressure of the vapour in the vapour chamber, for example without active heating of the vapour chamber. As described previously, in some embodiments the structure of the valve may aid dosing of vapour in the headspace of the vapour chamber into the flow passage.

In preferred embodiments, the valve consists of a single valve, wherein the valve, when closed, is configured to prevent passage of vapour from the vapour chamber into the flow passage to both the inlet and the outlet, and wherein, when open, the valve is configured to permit vapour from the vapour chamber to be carried to the outlet by the carrier gas flow. Thus, the single valve may be configured to close the only opening between vapour chamber and the flow passage.

As will be appreciated, the vapour chamber of the vapour storage module may comprise any suitable container that is impermeable to the vapour that is contained within the vapour chamber. Suitably, the valve may provide the only entrance and exit for vapour into or out from the vapour chamber, for example the valve may suitably comprise the only pathway for fluid flow between the vapour chamber and the flow passage. In some embodiments the vapour chamber may comprise a sealable port separate from the valve, wherein the port is not configured to be in fluid communication with the flow passage and the detection apparatus, but may for example be used to provide the source of vapour, e.g. a calibrant material, into or out from the vapour chamber during servicing.

The source of vapour within the vapour chamber may be provided in any suitable way. For example, the source of vapour may comprise a liquid that provides vapour pressure in the headspace of the vapour chamber so that when the valve is opened the vapour is provided into the flow passage. The vapour chamber may suitably contain an absorbent material that contains, for example that is saturated with, a liquid to be provided to the -13 -detection apparatus in the form of a vapour, for example wherein the liquid comprises a calibrant or dopant, preferably a calibrant. Thus the vapour chamber may comprise a calibrant or dopant in the liquid phase, wherein the liquid is immobilised by absorption, but where vapour evaporated from the liquid can fill the headspace of the vapour chamber as a result of the liquid's inherent vapour pressure. It will be appreciated that the headspace is suitably located adjacent the valve to allow the vapour in the headspace to pass through the valve when it is open.

Thus, the vapour storage module may comprise a calibrant sample stored in the vapour chamber. The calibrant sample may be a liquid at ambient temperature and pressure that has a vapour pressure of at least 35 kPa at 25 °C. For example, in preferred embodiments the calibrant sample comprises or consists essentially of isofluorane. Ass has been described herein, the present detection system and vapour storage module is particularly advantageous when a high volatility material, such as isofluorane, is used in the vapour chamber.

The flow passage may extend adjacent to an external wall of the vapour chamber within the housing from the inlet to the outlet. The flow passage may for example extend substantially parallel to one or more walls, e.g. external walls, of the vapour chamber (e.g. parallel to at least two or at least three walls of the vapour chamber). Relative to a maximum internal dimension D of the vapour chamber (e.g. the length from the valve to an end of the chamber opposite the valve), the flow passage between the inlet and the outlet may remain within a distance D from the vapour chamber, for example within a distance of 1/2D (i.e. half of the maximum internal dimension D of the vapour chamber). For example, the flow passage may at least partially surround the vapour chamber. Such arrangements allow for a compact vapour storage module containing both the vapour chamber and the absorbent material arranged to absorb vapour that is present in the flow passage. A more compact vapour absorption module can have the benefit of saving space within the detection system, which may be important for portable or handheld detectors, and also provides a smaller removable module, increasing storage efficiency for removed vapour storage modules awaiting servicing or serviced modules stored for use in replacing vapour storage modules in active detection systems. Thus, the vapour chamber may take up at least 10% of the internal volume of the housing of the vapour -14 -storage module, which may be possible due to the advantageous arrangement of the flow passage around the vapour chamber. For example, the vapour chamber may take up at least 20% of the internal volume of the housing of the vapour storage module, for example at least 30%, such as at least 35%. The vapour chamber may take up from 10% to 60% of the internal volume of the housing of the vapour storage module, for example from 20% to 40% of the internal volume of the housing of the vapour storage module The vapour chamber may have a first end and a second end opposite the first end. The valve may be arranged at the first end of the vapour chamber. An inlet portion of the flow passage can extend from the inlet to the valve, and an outlet portion of the flow passage can extend from the valve to the outlet, where the inlet and the outlet are arranged at the second end of the vapour chamber. The inlet portion of the flow passage and/or the outlet portion of the flow passage may extend adjacent and/or parallel to a lateral wall of the vapour chamber that extends between the first and the second end of the vapour chamber.

The absorbent material may be arranged in any suitable way so as to absorb vapour that is present in the flow passage to inhibit diffusion of vapour in the flow passage into the detection apparatus. When the valve is closed and the flow through the flow passage is stopped (for example when the stored vapour, e.g. calibrant, is no longer needed), it is desirable to avoid leakage of vapour into the detection apparatus from the vapour storage module by diffusion, which can interfere with operation of the detection apparatus. As will be appreciated, the flow passage and the vapour absorbent material are configured so that when there is a flow of carrier gas carrying vapour through the flow passage, the vapour can pass through the flow passage past the absorbent material without significant absorption of the vapour, i.e. so that the vapour can be delivered from the vapour chamber through the flow passage to the detection apparatus via the vapour inlet of the detection apparatus. However, when no flow of carrier gas is provided through the flow passage, the absorbent material is configured to absorb vapours present in the flow passage to inhibit diffusion of the vapour into the detection apparatus through the vapour inlet or the flow outlet. In this way, the absorbent material can prevent unwanted leaks of vapour from the vapour chamber into the detection apparatus.

-15 -The flow passage may suitably comprise a conduit having one or more walls configured to contain a flow of gas and vapour within the conduit in order to direct flow along the flow passage. Thus, a conduit may comprise an enclosed passageway for directing and containing flow travelling along a given flow path such as along the flow passage.

The flow passage may comprise a conduit having a vapour permeable wall, wherein the vapour absorbent material is configured to absorb vapour from the flow passage through the vapour permeable wall. The absorbent material may be configured to absorb vapour in the flow passage downstream of the valve in the flow passage and optionally also upstream of the valve in the flow passage. For example, the inlet portion of the flow passage may comprise a first absorbent material configured to absorb vapour present in the inlet portion to inhibit diffusion of vapour in the inlet portion to the inlet of the flow passage, and the outlet portion of the flow passage may comprise a second absorbent material configured to absorb vapour present in the outlet portion to inhibit diffusion of vapour in the outlet portion to the outlet of the flow passage. Suitably, each of the inlet portion and the outlet portion may comprise a conduit having a vapour permeable wall to permit the first and second absorbent materials to absorb vapour from the flow passage through the vapour permeable wall. The first and second absorbent materials may be the same or different, but preferably comprise the same material.

The absorbent material may comprise any material suitable to take in the vapour and avoid its release into the flow passage. The absorbent material may for example comprise a porous absorbent material. In embodiments, the absorbent material (for example the first and/or second vapour absorbent materials) may comprise carbon, for example activated carbon (e.g. charcoal/activated charcoal) or may comprise a molecular sieve material for example zeolite.

The absorbent material may be arranged with the flow passage in any way that permits vapour to pass from the flow passage to the absorbent material when there is no flow of carrier gas through the flow passage. The flow passage may extend through the vapour absorbent material, so that the vapour absorbent material surrounds the flow passage. For example, the flow passage may comprise a bore formed through a block of the vapour absorbent material so that a vapour permeable wall of the flow passage permits -16 -the absorbent material to absorb vapour that is present in the flow passage. Alternatively, the flow passage may comprise a channel formed on a surface of a vapour impermeable material, wherein an open side of the channel comprises a vapour permeable wall, for example a vapour permeable film, separating the channel from the vapour absorbent material.

The detection system may comprise a controller configured to control operation of the detection apparatus and the vapour storage module. For example, the controller may be configured to control operation of the detection apparatus to ionise and analyse vapour from the vapour chamber, and this may be synchronised with controlling operation of the valve of the vapour storage module and one or more flow providers to provide a flow of vapour (e.g. calibrant) from the vapour chamber, via the flow passage, to the vapour inlet and to the detection apparatus (e.g. to an ionisation region as described). In this way, the controller may be configured to control operation of the valve, one or more flow providers, and the detection apparatus (e.g. operation of the detection apparatus to ionise and analyse vapour) to analyse vapour provided from the vapour chamber. Preferably the vapour from the vapour chamber is a calibrant, and the controller is configured to calibrate the detection apparatus in response to performing analysis of the calibrant provided to the detection apparatus from the vapour chamber. Thus, the controller may be configured to operate the detection system in a calibration mode in which the controller is configured to: (i) open the valve to release a calibrant vapour into the flow passage, whilst operating one or more flow providers to provide a carrier gas flow through the flow passage to carry the calibrant vapour to the vapour inlet of the detection apparatus; (ii) operate the detection apparatus to analyse the calibrant vapour; and (iii) to calibrate the detection apparatus based on the analysis of the calibrant vapour. Suitably, the detection apparatus may comprise an IMS and step (ii) may comprise operating an ioniser to ionise the calibrant vapour and obtaining ion mobility spectrometry data based on the ionised calibrant. Step (iii) may comprise adjusting one or more detection parameters of the detection apparatus, for example in an IMS this may comprise adjusting detection windows (a range of drift times that are considered to represent a material of interest) to shift or adjust the width of detection windows.

The calibration mode may, for example, be activated in response to user input, a set time -17 -period expiring, a detected change in environmental conditions such as temperature, pressure or humidity, or a change in the operating parameters of the detection apparatus. The controller may be configured to monitor analysis of the calibrant or to monitor normal operation of the detection apparatus to assess the state of the vapour storage module, for example to determine if a low quantity of calibrant remains, or if calibrant is detected outside of a calibration mode, that the absorbent material may be saturated and need replacement or servicing. of the detection apparatus. The controller may be configured to provide a notification to a user when replacement or servicing of the vapour storage module is required, which may be in response to an assessment of the state of the vapour storage module determined by the detection apparatus, or after a set time period after a vapour storage module is coupled to the detection apparatus.

The controller described herein may suitably be provided by any appropriate control logic, such as analogue control circuitry and/or digital processors, examples include field programmable gate arrays, FPGA, application specific integrated circuits, ASIC, a digital signal processor, DSP, or by software loaded into a programmable processor. Aspects of the disclosure comprise computer program products, and may be recorded on non-transitory computer readable media, and these may be operable to program a processor to perform any one or more of the methods described herein.

A further aspect provides a vapour storage module as defined herein configured to store vapour for delivery to a detection apparatus. The vapour storage module may comprise a vapour chamber configured to store a source of vapour for delivery to the detection apparatus; and a flow passage comprising an inlet configured to receive a carrier gas flow from the detection apparatus and an outlet configured to provide an outlet flow to the detection apparatus, the flow passage separated from the vapour chamber by a valve configured to control the passage of vapour from the vapour source into the flow passage; an absorbent material in fluid communication with the flow passage configured to inhibit diffusion of vapour in the flow passage into the detection apparatus; and a housing containing the vapour chamber, the flow passage and the absorbent material, the housing comprising a first interface portion comprising a first connector at the inlet of the flow passage and a second connector at the outlet of the flow passage; wherein the vapour storage module is removably couplable to the detection apparatus by the first -18 -interface portion, the first interface portion configured to couple with a second interface portion of the detection apparatus to align the first connector with a flow outlet of the detection apparatus to provide a sealed connection, and to align the second connector with a vapour inlet of the detection apparatus to provide a sealed connection.

As has been discussed, where a vapour source, such as a calibrant, is used that has a high vapour pressure, this can cause problems with leakage of the vapour from a vapour store into a detection apparatus. The leakage can be minimised by the arrangements described herein, and in particular the limitation of the system to having a single point of fluid communication between the vapour chamber and the detection apparatus that is controlled by a valve. Such an arrangement is particularly advantageous in the context of using highly volatile vapour sources (e.g. calibrant such as isofluorane), this is because points where leaks from a vapour chamber may occur are minimised, whilst at the same time, the high vapour pressure of the vapour source allows for effective diffusion of the vapour from the vapour chamber, and so passing a flow through the vapour chamber (as might be done where more than one inlet/opening in a vapour chamber is present) is not necessary to obtain sufficient vapour release from the vapour chamber.

Thus, a further aspect provides a vapour generator for delivery of vapour to a detection apparatus, the vapour generator comprising a vapour chamber configured to store a source of vapour for delivery to the detection apparatus; a flow passage comprising an inlet configured to receive a carrier gas flow and an outlet configured to provide an outlet flow to the detection apparatus, the flow passage coupled to the vapour chamber by a single valve disposed between the inlet and the outlet, wherein the valve, when closed, is configured to prevent passage of vapour from the vapour chamber into the flow passage to both the inlet and the outlet, and wherein, when open, the valve is configured to permit vapour from the vapour chamber to be carried to the outlet by the carrier gas flow; an absorbent material in fluid communication with the flow passage and configured to inhibit diffusion of vapour in the flow passage to the inlet or to the outlet and into the detection apparatus.

The vapour generator may comprise a flow provider configured to provide a flow of carrier gas to the inlet of the flow passage, past the valve and through the outlet of the -19 -flow passage to a vapour inlet, wherein when the valve is open, vapour exiting the vapour source is carried by the carrier gas to the detection apparatus through the outlet of the flow passage and, when the valve is closed, the flow provider can provide a carrier gas flow from the inlet of the flow passage to the outlet of the flow passage past the closed valve.

The vapour chamber, the flow passage and the absorbent material may be substantially as defined previously herein. The vapour generator may also comprise a vapour storage module as defined previously herein, for example a removable vapour storage module. The vapour generator may also form part of a detection system as defined previously herein, and for example my be configured to deliver vapour from the vapour chamber to a detection apparatus as defined previously, for example, an ion mobility spectrometer.

A further aspect provides a method of servicing a vapour generator of a detection system configured to provide a calibrant or a dopant to a detection apparatus, the method comprising: detaching a vapour storage module coupled to the detection apparatus, the vapour storage module comprising a vapour chamber configured to store a source of calibrant or dopant, and a vapour absorbent material configured to absorb vapour released from vapour chamber to inhibit diffusion of vapour from the vapour storage module into the detection apparatus; coupling to the detection apparatus a replacement vapour storage module, wherein compared to the vapour storage module removed from the detection apparatus the replacement vapour storage module: contains an increased quantity of calibrant or dopant; and/or comprises vapour absorbent material having increased ability to absorb vapour.

The method may further comprise further comprise servicing the vapour storage module removed from the detection apparatus by: refilling the vapour chamber with calibrant or dopant; and/or treating or replacing the vapour absorbent material to enhance its ability to absorb vapour.

As will be appreciated, the detection system, the detection apparatus and/or the vapour storage module may be as defined previously herein.

-20 -

Brief Description of Figures

Examples of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic illustration of a detection system comprising a vapour storage module and a detection apparatus; Figure 2 shows a schematic illustration of the detection system of Figure 1, in which the vapour storage module is coupled to the detection apparatus; Figure 3 shows a schematic illustration of a valve that separates a vapour chamber from a flow passage, in which the valve is in the closed configuration; Figure 4 shows a schematic illustration of the valve shown in Figure 3 in which when the valve is in the open position; Figure 5 shows a schematic illustration of the valve shown in Figure 4, illustrating the vapour flow; Figure 6 shows a schematic illustration of an alternative valve that separates a vapour chamber from a flow passage, in which the valve is in the closed configuration; and Figure 7 shows a schematic illustration of the valve shown in Figure 6, illustrating the vapour flow.

In the drawings like reference numerals are used to indicate like elements.

Specific Description

The present disclosure relates to detection systems and removable vapour storage modules, as well as vapour generators for detection systems.

Figure 1 shows a schematic illustration of a detection system 100 comprising a vapour storage module 102 and a detection apparatus 202. The vapour storage module 102 comprises vapour chamber 104 containing a vapour source 105 which may comprise an absorbent that is saturated with a liquid such as a calibrant liquid. The vapour source 105 in the vapour chamber 104 is configured to provide a vapour in the headspace between -21 -the vapour source 105 and a valve 110 that is configured to seal the vapour chamber 104 to prevent vapour leaving the vapour chamber 104. The valve 110 is configured to control passage of vapour from the vapour source 105 out of the vapour chamber 104 into a flow passage 106.

The flow passage 106 extends from an inlet 107, past the valve 110 to an outlet 108. The vapour chamber 104 has a first end that comprises the valve 110, and a second end opposite the first end. The flow passage 106 extends adjacent to a lateral wall of the vapour chamber 104 from the inlet 107 to the valve 110, and from the valve 110, adjacent to a lateral wall of the vapour chamber to the outlet 108. Thus, the flow passage 106 forms a U shape, where the inlet 107 and the outlet 108 are located at a common surface of the housing of the vapour storage module 102 comprising the first interface portion (e.g. connectors 122 and 124) for coupling with the detection apparatus, and the flow passage 106 extends around the vapour chamber 104 past the valve 110 at a first end of the vapour chamber distal from the common surface. For example, the flow passage 106 forms three sides of a rectangle, where the vapour chamber 104 is surrounded by the flow passage 106 on three sides.

The flow passage comprises an inlet portion 112 that extends from the inlet 107 to the valve 110, and an outlet portion 116 that extends from the valve 110 to the outlet 108. The inlet portion 112 of the flow passage 106 comprises a first absorbent material 114 (which may for example comprise carbon such as activated carbon/charcoal). The first absorbent material 114 is in fluid communication with the inlet portion 112 to permit vapour that is present in the flow passage 106 to pass through a vapour permeable wall of the inlet portion 112 to the first absorbent material 114. Similarly, the outlet portion 116 of the flow passage 106 comprises a second absorbent material 118 (which may also for example comprise carbon such as activated carbon/charcoal). The second absorbent material 116 is in fluid communication with the outlet portion 116 to permit vapour that is present in the flow passage 106 to pass through a vapour permeable wall of the outlet portion 116 to the second absorbent material 118. The first and second absorbent materials 114/118 are configured to inhibit leakage of vapour present in the flow passage 104 to the inlet 107 or the outlet 108 when no flow is provided through the flow passage 106 (for example when delivery of vapour from the vapour source 105 to the detection -22 -apparatus 202 is not required). It will be appreciated that while flow directions are shown in Figure 1, this is for illustrative purposes and the flow from the inlet 107 to the outlet 108 is provided only when the vapour storage module 102 is coupled to the detection apparatus 202, for example as shown in Figure 2.

A first interface portion of the vapour storage module 102 comprises a first connector 124 at the inlet 107 of the flow passage 106, and a second connector 122 at the outlet 108. The first and second connectors 124/122 may comprise plug portions that protrude from the housing of the vapour storage module 102. The first connector 124 and the second connector 122 can therefore comprise plug portions that protrude from the housing of the vapour storage module 102 for coupling with corresponding socket portions at a third connector 224 and a fourth connector 222 of the detection apparatus. While Figure 1 shows plug portions on the interface of the vapour storage module 102, it will be appreciated that the plug portions may be provided on the detection apparatus 202 and the first and second connectors may comprise corresponding socket portions.

As shown in Figure 1, the vapour storage module 102 is detached from the detection apparatus 202. As shown in Figure 2, the vapour storage module 102 may be coupled with the detection apparatus 202 to connect the inlet 107 of the flow passage 106 with the flow outlet 207 of the detection apparatus 202, and to connect the outlet 108 of the flow passage 106 with the vapour inlet 208 of the detection apparatus 202 via the first connector 124, the second connector 122, the third connector 224 and the fourth connector 224. As shown in Figures 1 and 2, the vapour storage module 102 fits into a recess of an interface portion of the detection apparatus 202 to align the flow outlet 207 with the inlet 107 and the vapour inlet 208 with the outlet 108 (and to align the corresponding plug and socket connectors).

In Figures 1 and 2, only an interface portion of the detection apparatus 202 is shown. However, it will be appreciated that the vapour inlet 208 of the detection apparatus may be configured to provide vapour from the vapour storage module 102 into the detection apparatus as described elsewhere herein.

Figure 3 shows a schematic illustration of an embodiment of the valve 110. Figure 3 -23 -shows the flow passage 106 passing the valve, where the valve separates the flow passage 106 from an internal volume of the vapour chamber 104. The valve comprises a shaft 300 that is acted on by a solenoid (not shown) to move the valve down into the vapour chamber 104. The vapour chamber 104 comprises a vapour source 315, and a headspace 314 between the vapour source 315 and the valve.

The valve comprises environmental seal 304 that may comprise one more radial seals that surround the shaft 300 to prevent leakage of vapour or gas into or out from the flow passage 106 pas the shaft. One or more radial seals 306 are also provided around the shaft 300 to prevent passage of vapour from the vapour chamber 104 past the shaft 300 into the flow passage 106. The shaft 300 comprises a neck portion 302, which comprises a region in which the diameter of the shaft 300 is smaller than the remainder of the shaft 300.

The shaft 300 in Figure 3 also comprises a flange portion 316 that extends out radially from lower end of the shaft 300 within the vapour chamber 104. Face seal 308 provides a seal between an upper surface 318 of the flange portion 316 and an upper internal wall 310 of the vapour chamber 104 to prevent passage of vapour from a headspace 314 of the vapour chamber 104 into the flow passage 106 past the shaft 300. The valve comprises an energised seal where a biasing member such as a spring is configured to pull the shaft 300 in a direction out from the vapour chamber 104, which maintains a seal between the upper surface 318 of the flange portion 316 and the face seal 308.

As shown in Figure 3, the shaft 300 may move along its longitudinal axis through a passageway or bore through the material of the housing 330. The material from which the housing surrounding the shaft is formed should be less hard than the material form which the shaft 300 is made. For example, the shaft may be made from steel (e.g. stainless steel) and the housing 330 surrounding the shaft 300 may be made from a plastic such as PEEK. It has been found that this combination avoids scratches forming on the shaft that cause leaks from the vapour chamber 104 past the shaft 300 into the flow passage.

-24 -Figure 4 shows a schematic illustration of the valve shown in Figure 3 when the valve is open. The solenoid acts on the shaft 300 to move the shaft 300 down into the headspace 314 of the vapour chamber 104. This aligns the neck portion 302 with the radial seal 306, allowing the passage of vapour from the headspace 314 into the flow passage 106. In addition, the flange portion 316 at the end of the shaft 300 moves into the vapour chamber 104 to disengage the seal between the upper surface 318 of the flange portion 316 and the face seal 308. It will be appreciated that when the solenoid is not powered, the biasing member of the energised seal will pull the shaft 300 into the closed position shown in Figure 3, maintaining a seal on the vapour chamber 104 in the absence of power being provided to the valve.

The flange portion 316 may also serve to aid dosing of vapour in the headspace 314 of the vapour chamber 104 into the flow passage 106. For example, when the valve is open, the flange portion 316 of the shaft 300 is pushed into the vapour chamber 104 to provide a spacing in the headspace 314 between the upper surface of the flange portion 318 and the face seal 308/upper wall 310 of the vapour chamber. The headspace 314 between the upper surface of the flange portion 318 and the face seal 308/upper wall 310 may then fill with vapour from the headspace 314 and the vapour source 315 so that when the valve is closed (i.e. when the flange portion 316 is moved towards the face seal 308/upper wall 310 of the vapour chamber) the flange portion 316 pulls vapour in the spacing towards the exit of the vapour chamber 104 and towards the flow passage 106 (for example by movement from the configuration shown in Figure 4 to that of Figure 3). Thus, the flange portion of the shaft can also aid in providing more reliable dosing of vapour from the vapour chamber 104 into the flow passage 106.

Figure 5 shows the open valve shown in Figure 4, further illustrating the flow 342 of vapour in the headspace 314 of the vapour chamber 104 into the flow passage 106 when the valve is open. A carrier gas flow 340 though the flow passage 106 then carries the vapour from the vapour chamber 104 along the flow passage 106 to the outlet 108 in a vapour/carrier gas flow 344.

Figure 6 shows an alternative valve configuration that corresponds to that shown in Figures 3 to 5, with the exception that the valve comprises a shaft 400 that does not -25 -comprise a flange portion as shown in Figures 3 to 5. The shaft 400 comprises a straight shaft that engages environmental radial seal 304 to prevent leaks out from or into the flow passage 106 past the shaft 400. In the closed configuration shown in Figure 6, the shaft 400 also engages radial seal 306 to prevent passage of vapour from the vapour chamber 104 into the flow passage 106 past the shaft 400.

Figure 7 shows a schematic illustration of the valve shown in Figure 6 when the valve is opened. The shaft 400 moves out away from the vapour chamber 104 to disengage with the radial seal 306. This permits a flow 342 of vapour from the headspace 314 of the vapour chamber to flow into the flow passage 106. As explained in relation to Figure 5, a carrier gas flow 340 though the flow passage 106 then carries the vapour from the vapour chamber 104 along the flow passage 106 to the outlet 108 in a vapour/carrier gas flow 344.

While both radial seals 306 and face seals 308 are shown in Figures 3 to 5, it will be appreciated that in some instances only the radial seal 306 or only the face seal 308 may be used. It will also be appreciated that while a single seal is referred to, each seal may comprise one seal member or more than one seal member. The seals may each comprise PTFE seals.

Although embodiments of the disclosure have been described as having particular application in ion mobility spectrometers, the apparatus and methods described may be applied in other analysis systems where there is a need to provide vapours such as calibrants to a detection apparatus. As will be appreciated a vapour may comprise a substance in its gaseous phase at a temperature lower than its critical point.

In general, apparatus features described herein may be provided as method features, and vice versa.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently. Other examples and variations will be apparent to the skilled addressee in the context of the present disclosure.

Claims

-26 -CLAIMS: 1. A detection system comprising: a detection apparatus; and a vapour storage module configured to store vapour for delivery to the detection apparatus, the vapour storage module comprising: a vapour chamber configured to store a source of vapour for delivery to the detection apparatus; a flow passage comprising an inlet configured to receive a carrier gas flow from the detection apparatus and an outlet configured to provide an outlet flow to the detection apparatus, the flow passage separated from the vapour chamber by a valve configured to control the passage of vapour from the vapour source into the flow passage; an absorbent material in fluid communication with the flow passage configured to inhibit diffusion of vapour in the flow passage into the detection apparatus; and a housing containing the vapour chamber, the flow passage and the absorbent material, the housing comprising a first interface portion comprising a first connector at the inlet of the flow passage and a second connector at the outlet of the flow passage; wherein the vapour storage module is removably coupled to the detection apparatus, the detection apparatus comprising a second interface portion configured to couple with the first interface portion of the vapour storage module, the first and second interface portions configured to align the first connector with a flow outlet of the detection apparatus to provide a sealed connection, and to align the second connector with a vapour inlet of the detection apparatus to provide a sealed connection.
2. The detection system of claim 1, wherein the flow passage extends adjacent to an external wall of the vapour chamber within the housing from the inlet to the outlet.
3. The detection system of claim 1 or claim 2, wherein the vapour inlet of the detection apparatus is configured to provide vapour from the flow passage to the -27 -detection apparatus for calibrating the detection apparatus.
4. The detection system of claim 3, wherein the detection apparatus comprises an ion detection apparatus, for example an ion mobility spectrometer, a mass spectrometer, or a combination thereof, and the vapour inlet of the detection apparatus is configured to provide vapour received from the flow passage to an ionisation region of the detection apparatus.
5. The detection system of any one of the preceding claims, comprising a flow provider configured to provide a flow of carrier gas to the inlet of the flow passage, past the valve and through the outlet of the flow passage to the vapour inlet, wherein when the valve is open, vapour exiting the vapour source is carried by the carrier gas to the detection apparatus through vapour inlet.
6. The detection system of any one of the preceding claims, wherein the detection apparatus is configured to provide the carrier gas flow from a source of gas within the detection apparatus, or from an ambient environment in which the detection system is operated.
7. The detection system of any one of the preceding claims, wherein the valve is a solenoid valve, for example a solenoid valve comprising an energised seal configured to maintain the valve in a closed configuration when the solenoid valve is not powered.
8. The detection system of claim 7, wherein the valve comprises a shaft and one or more radial and/or face seals configured to prevent vapour from exiting the vapour chamber when the valve is closed.
9. The detection system of claim 8, wherein the valve comprises one or more radial seals surrounding the shaft, and the shaft comprises a neck portion in which the diameter of the shaft is reduced so that when the neck portion aligns with the one or more radial seals, the valve is opened.
10. The detection system of claim 8 or claim 9, wherein the one or more radial and/or -28 -face seals are PTFE seals.
11. The detection system of any one of claims 8 to 10, wherein the valve comprises an enclosure having a passage through which the shaft can move axially to open and close, wherein the shaft is formed from a material that is harder than the material from which the enclosure is formed, for example, wherein the shaft is made from steel, for example stainless steel, and the enclosure is made from plastic, for example PEEK.
12. The detection system of any one of claims 8 to 11, wherein the shaft comprises first end on which the solenoid acts to move the shaft axially, and a second end that enters an entrance to the vapour chamber to seal the vapour chamber, wherein the second end comprises a flange portion that extends radially from around the second end, optionally wherein the flange portion forms a face seal against an internal wall of the vapour chamber when the valve is closed.
13. The detection system of any one of the preceding claims, wherein the flow passage comprises a conduit having a vapour permeable wall, wherein the vapour absorbent material is configured to absorb vapour through the vapour permeable wall.
14. The detection system of claim 13, wherein the flow passage extends through the vapour absorbent material, so that the vapour absorbent material surrounds the flow passage; or wherein the flow passage comprises a channel formed on a surface of a vapour impermeable material, wherein an open side of the channel comprises a vapour permeable wall, for example a vapour permeable film, separating the channel from the vapour absorbent material.
15. The detection system of any one of the preceding claims, comprising a calibrant sample stored in the vapour chamber, wherein the calibrant sample has a vapour pressure of at least 35 kPa at 25 °C, for example wherein the calibrant sample comprises or consists essentially of isofluorane.
16. The detection system of any one of the preceding claims, wherein the first and/or second vapour absorbent materials comprise carbon, for example activated carbon.
-29 - 17. The detection system of any one of the preceding claims, wherein the valve consists of a single valve, wherein the valve, when closed, is configured to prevent passage of vapour from the vapour chamber into the flow passage to both the inlet and the outlet, and wherein, when open, the valve is configured to permit vapour from the vapour chamber to be carried to the outlet by the carrier gas flow.
18. A vapour storage module configured to store vapour for delivery to a detection apparatus, the vapour storage module comprising: a vapour chamber configured to store a source of vapour for delivery to the detection apparatus; and a flow passage comprising an inlet configured to receive a carrier gas flow from the detection apparatus and an outlet configured to provide an outlet flow to the detection apparatus, the flow passage separated from the vapour chamber by a valve configured to control the passage of vapour from the vapour source into the flow passage; an absorbent material in fluid communication with the flow passage configured to inhibit diffusion of vapour in the flow passage into the detection apparatus; and a housing containing the vapour chamber, the flow passage and the absorbent material, the housing comprising a first interface portion comprising a first connector at the inlet of the flow passage and a second connector at the outlet of the flow passage; wherein the vapour storage module is removably couplable to the detection apparatus by the first interface portion, the first interface portion configured to couple with a second interface portion of the detection apparatus to align the first connector with a flow outlet of the detection apparatus to provide a sealed connection, and to align the second connector with a vapour inlet of the detection apparatus to provide a sealed connection.
19. The vapour storage module of claim 18, wherein the vapour storage module is as further defined in any one of claims 7 to 17.
20. The vapour storage module of claim 18 or claim 19 or the detection system of any one of claims 1 to 17, wherein the vapour chamber takes up at least 20% of the internal -30 -volume of the housing of the vapour storage module, for example wherein the vapour chamber takes up from 20% to 40% of the internal volume of the vapour storage module.
21. A vapour generator for delivery of vapour to a detection apparatus, the vapour generator comprising: a vapour chamber configured to store a source of vapour for delivery to the detection apparatus; a flow passage comprising an inlet configured to receive a carrier gas flow and an outlet configured to provide an outlet flow to the detection apparatus, the flow passage coupled to the vapour chamber by a single valve disposed between the inlet and the outlet, wherein the valve, when closed, is configured to prevent passage of vapour from the vapour chamber into the flow passage to both the inlet and the outlet, and wherein, when open, the valve is configured to permit vapour from the vapour chamber to be carried to the outlet by the carrier gas flow; an absorbent material in fluid communication with the flow passage and configured to inhibit diffusion of vapour in the flow passage to the inlet or to the outlet and into the detection apparatus.
22. The vapour generator of claim 21, comprising a flow provider configured to provide a flow of carrier gas to the inlet of the flow passage, past the valve and through the outlet of the flow passage to a vapour inlet, wherein when the valve is open, vapour exiting the vapour source is carried by the carrier gas to the detection apparatus through the outlet of the flow passage and, when the valve is closed, the flow provider can provide a carrier gas flow from the inlet of the flow passage to the outlet of the flow passage past the closed valve.
23. The vapour generator of claim 21 or claim 22, wherein the vapour generator comprises a removable vapour storage module or a detection system as further defined in any one of claims 2 to 16.
24. A method of servicing a vapour generator of a detection system configured to provide a calibrant or a dopant to a detection apparatus, the method comprising: detaching a vapour storage module coupled to the detection apparatus, the -31 -vapour storage module comprising a vapour chamber configured to store a source of calibrant or dopant, and a vapour absorbent material configured to absorb vapour released from vapour chamber to inhibit diffusion of vapour from the vapour storage module into the detection apparatus; coupling to the detection apparatus a replacement vapour storage module, wherein compared to the vapour storage module removed from the detection apparatus the replacement vapour storage module: contains an increased quantity of calibrant or dopant; and/or comprises vapour absorbent material having increased ability to absorb vapour.
25. The method of claim 24, further comprising servicing the vapour storage module removed from the detection apparatus by: refilling the vapour chamber with calibrant or dopant; and/or treating or replacing the vapour absorbent material to enhance its ability to absorb vapour.
26. The method of claim 24 or claim 25, wherein the detection system and/or the vapour storage module are as defined in any one of claims 1 to 23.