A valve assembly for an analytical system

Abstract

A valve assembly for use with an analytical system comprises first (102) and second (104) members, with each member having a through-bore (106, 108) from a first face to a second face. The members are stacked together with their respective first faces in contact to form a seal between them, and one of the members is slidably movable, relative to the other, between at least two configurations: a first configuration in which the through-bores are fluidically connected, and a second configuration in which the through-bores are sealed from each other.

Description

A VALVE ASSEMBLY FOR AN ANALYTICAL SYSTEMTECHNICAL FIELD

[0001] This disclosure relates to a valve assembly for an analytical system.BACKGROUND

[0002] Analytical systems, such as a gas chromatography-mass spectrometry (GC-MS) apparatus, a liquid chromatography-mass spectrometry (LC-MS) apparatus, or an ion chromatography-mass spectrometry (IC-MS) apparatus, may include an interface between two neighbouring apparatuses with a transfer line therebetween. Forming and interrupting a connection between the neighbouring apparatuses with the transfer line often comes with conflicting technical requirements. For example, some apparatuses in analytical systems demand that vacuums, temperatures, and / or pressures be maintained during use, while transfer lines that are convenient to connect and disconnect are generally desirable.

[0003] In some known GC-MS arrangements, a transfer line is connected between a column exiting an oven in a gas chromatograph and an ion source at a mass spectrometer. The ion source may be under vacuum (e.g., in electron impact mass spectrometry) and the GC column may need to be maintained at an appropriate temperature, usually between 100°C and 350°C.SUMMARY

[0004] The technical challenges associated with a transfer line interface in an analytical system may be addressed using a valve assembly that can switch between two states, one state which enables fluidic connection and one state which is sealed. The valve may achieve a connection that can be formed and interrupted without breaking vacuum states, without damaging or breaking the transfer line, and without significant heat loss to the apparatuses of the analytical system.

[0005] With that in mind the present disclosure relates to a valve assembly for use with an analytical system. The valve assembly comprises first and second members, which each define a through-bore from a first face to a second, opposite face. The first and second members are stacked together such that their respective first faces are in contact, forming a seal at the interface between the two members. One of the first and second members is slidably movable relative to the other. For example, the second member may be in a fixed position on an apparatus of the analytical system, the first member may be on a railed mount and free to slide over the second member, or vice versa. Alternatively, it will be appreciated that both members may be slidably movable relative to the other. The relative slidable movement of the first and second members enables the two members to switch between afirst configuration in which the through-bores are fluidically connected, i.e., the through-bores of the two members are aligned, and a second configuration in which the through-bores are sealed from each other, i.e., a surface of the first face of the first member opposes the through-bore of the second member. The slidable movement of the members to dispose the stack in at least two configurations may be either rotational / arcuate movement, linear movement, or a combination of the two. It will be appreciated that a modular and scalable nature of the valve assembly in this way may facilitate ease of replacement and / or ease of retrofitting onto existing analytical systems.

[0006] By using a slidable movement of the valve members to achieve the two configurations, sealing the valve does not require significant force which may deform the connecting material, as is otherwise common, for example, with screw type valves. The slidable movement of the valve instead enables a smooth and easy switching between the configurations, thereby improving both convenience and durability of the analytic system components, whilst still providing a good seal. Furthermore, the seal gets better with extended use, because the sliding members slightly wear over time to better fit one another. To strengthen the seal, force may be applied to the valve members using magnetic, pneumatic, or other common means, such as a clamp or spring. A vacuum cavity within the seal may also be used, for example, whereby the respective first face of one or both of the valve members is provided with a recess configured to constitute a vacuum cavity in cooperation with the opposing face / recess when the valve is in a sealed configuration. In such examples, the second member may comprise an additional through bore in connection with the vacuum cavity, configured to enable evacuation of the cavity formed by the one or two recesses (e.g., using a vacuum pump). Additionally, rollers, bearing, lubricants, or other suitable means may be used to reduce friction between the members and to improve the slidable movement and / or the seal performance.

[0007] In some examples, the first and / or the second member is at least substantially formed of ceramic material. A ceramic member may have properties advantageous to the analytical system, including thermal and electrical insulation. For example, electrical insulation can prevent electrical shorting, e.g., shorting of an ion source in the system, and thermal insulation reduces heat sinking during use. In such examples, the first face of each member may be precisely ground and polished ceramic, to provide a vacuum seal between the first faces of the members when they are in contact with one another. It will be appreciated that the first and second members may similarly be formed of precisely ground and polished and / or ceramic-coated metal components instead of being entirely formed of ceramic.

[0008] In some examples, the first face of each member may comprise a polished surface, having an average arithmetic roughness (that is, the arithmetic average of the absolutedeviation from the mean plane) and flatness (that is, the maximum deviation from the mean plane) to enable wringing between the polished surfaces when slid together under sufficient pressure to bring the surfaces into intimate contact and expel any fluid between the surfaces. In other words, the members with polished surfaces may adhere to each other in the same manner as gauge blocks or slip gauges. For example, a polished surface may have an arithmetic average roughness of less than or equal to 1 microinch (0.025pm), and / or a flatness deviation of less than or equal to 5 microinches (0.13pm). Advantageously, these surface conditions (i.e., of roughness and / or flatness deviation), when provided on the first faces of both members, allow for sufficient molecular attraction or surface tension between the members in a stack to effectively bond the surfaces when slid together under pressure. In other words, the above surface requirements facilitate effective wringing between the first and second member in the stack, which advantageously improves sealing between the first member to the second member.

[0009] Additionally, extended use of the polished surface (i.e., with surface conditions as described above) may further improve the seal and / or the ease of user manipulation, because the two surfaces may become smoother with use or otherwise better tailored to one another so as to more easily slide between configurations.

[0010] The members may be substantially cylindrical, e.g., for ease of manufacture, and to enable to first member to roll onto, or rotate atop, the second member to switch between the configurations of the valve. Nevertheless, the members may be of any suitable shape, such as rectangular or hexagonal.

[0011] In some examples, the valve assembly may comprise a holding member, for example a cage, configured to hold the stack of members. The holding member supports the members, and may be of any suitable form, such as a closed holding member with an opening to enable access and utilization of the valve, or a C-shaped holding member to enable ease of access and to provide an aperture for slotting one or both of the valve members into the holding member. Additionally, the holding member may facilitate the positioning of the members relative to one another during use, e.g., to ensure a seal is maintained between the faces of the two members.

[0012] The respective through-bores of the first and second members may differ in shape. In one example, the through-bore of the first member has a first shape, the first shape being defined by a first bore and a second bore. The first bore may be configured to receive a transfer line of a chromatography system, and the second bore may be configured to receive a sleeve of the transfer line (i.e., the second bore may be wider than the first bore). Additionally, or alternatively, the through-bore of the first member may have a tapered end at the second face of the first member. Advantageously, the tapered end guides the (sleeve of the) transfer line into the valve, to facilitate accurate placement of the transfer line within thevalve during insertion. It will be understood that accurate placement of the transfer line ensures a good connection with the valve, e.g., to maintain vacuums in the system, or to reduce bending and risk of breakage of the transfer line during the relative movement of the valve members and / or the transfer line. In some examples, the transfer line or other component of the apparatus may be sealed to the second face of the first member to ensure a vacuum seal, e.g., without the need for an O-ring, between the two apparatuses of the analytical system either side of the valve.

[0013] Similarly, the through-bore of the second member may have a second shape comprising a constant bore corresponding with the through-bore at the first face of the first member. The dimensions of the through-bore of the second member may match or correspond with the dimensions of an outflow end of the through-bore of the first member, and thus the environment for a gas or liquid passing through the valve and into the analytical apparatus is advantageously constant, for example of a substantially same or similar cross- sectional area. For example, the constant environment may prevent or minimise expansion of gas as it passes out of the transfer line and through the valve, which may allow better control of the sample and thereby may improve accuracy during sample analysis.

[0014] As described above, the through-bore of the first member may differ to the through- bore of the second member, and thus the first member and the second member may be distinguishable members having individual through-bores. In other examples, the first member and the second member may be of substantially identical shape. By providing two members with identical shape, the manufacturing process can be identical for both members, and thus the efficiency and cost of manufacturing the valve may be improved.

[0015] In some examples, the first member and second member may each define two through-bores, a through-bore of a first shape and a through-bore of a second shape. The first shape corresponds with an intended shape for the through-bore of first member, and the second shape corresponds an intended shape for the through-bore of the second member. In this way, the first and second members are identical, enabling efficient manufacturing and ease of replacement, whilst still providing any or all of the individual features as discussed above for each shape of the respective through-bores of the first and second members.

[0016] In some further examples, the first member comprises one or more channels connecting the (primary) through-bore of the first member to one or more additional openings in the first member. The one or more additional openings enable additional input options for the first member, such as the insertion of additional samples or control gases alongside the primary injectant of the valve. Furthermore, by providing a channel within the valve that connects to the through-bore of the first member, additional or control samples may be combined upon entry to second member, and can be injected into the apparatus of the analytical system with the same environment prior to entry.

[0017] Additionally or alternatively, additional through-bores can be provided in the first member to provide an additional configuration for the members to slidably move between. The additional configuration enables a multi-input valve, e.g., a 3-way valve, which may facilitate fast switching between different apparatuses in the analytical system, e.g., between different gas chromatography columns or between different sample introduction modes.

[0018] In some examples, the first and / or second member comprise features to facilitate alignment of the components. In particular, the valve may comprise one or more magnets disposed in each of the members, such that the magnets define at least one of the configurations of the valve. The configuration of the magnets guides an alignment of the two members into one or more of the configurations of the valve, e.g., by providing opposite or same poles in respective portions of the members to magnetically attract the members to the aligned position. Additionally or alternatively, the magnets may be orientated relative to each other to repel one another when aligned in the stack, and therefore may facilitate slidable movement of the two members between configurations of the valve, and / or may facilitate detachment of the two members from one another. In some examples, two or more magnets may be provided in one or both of the members, to facilitate alignment into multiple different configurations. Furthermore, in any of the examples relating to magnetic attraction as discussed herein, a magnetic or magnetisable part may be used in place of a magnet in one of the members. For example, a magnetic part in one member may be magnetically attracted to a counterpart magnet in the other member, thereby guiding an alignment of the two members into one or more configurations of the valve. In a specific example, there may be one magnet and a corresponding magnetisable counterpart. In other examples, there may be any combination of one or more of pairs of magnets and one or more pairs of a magnet and a magnetisable part provided to define one or more configurations of the valve. It will be appreciated that other alignment features suitable to achieve the auto-alignment are also considered, such as a spring pin, a spring detent, or a hard stop.

[0019] The disclosure also relates to an analytical system comprising one or more analytical devices, e.g., a GC-MS system comprising a GC device connected via a transfer line to a MS device. At least one of the analytical devices comprises the valve assembly as described above, and the valve is configured to selectively open and close a fluid port of the analytical device. The second member may be fixed to the respective analytical device. For example, the second member may be brazed to the analytical device or sealed thereto with an O-ring, gasket, a screw profile, or by another method known in the art. Similarly, the through-bore of the second member may be in fluidic connection with an ion source of the analytical device. Advantageously, by implementing the valve as described herein in a GC- MS system, the GC column exiting the GC oven can be connected through a transfer line to the ion source of the Mass Spectrometer without breaking the vacuum in the ion source or inthe ion optics, without requirement for additional tools, without deformity to components, and without damage to the transfer line.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Disclosed implementations will now be described by way of example to illustrate aspects of the disclosure and with reference to the accompanying drawings, in which: Fig. 1A illustrates a perspective view of a valve assembly;Fig. 1B illustrates a perspective view of first and second members of the valve assembly of Fig. 1A;Figs. 10 and 1 D illustrate perspective views, respectively, of the first and second members of the valve of Fig. 1A;Figs. 2A and 20 illustrate a cross-sectional top views of a variant of the valve assembly of Fig. 1A;Figs. 2B and 2D illustrate a cross-sectional side views of the first and second members of Figs. 2A and 20 respectively;Figs. 2E and 2F illustrate perspective views, respectively, of the second and the first members of the valve of Fig. 2A;Figs. 3A and 3B illustrate cross-sectional and top views, respectively, of a variant of the first member of Fig. 1A;Fig. 30 illustrates a perspective view of a valve assembly with the first member of Fig. 3A;Figs. 4A and 4B illustrate cross-sectional and top views of a variant of the valve members of Fig. 1A;Fig. 40 illustrates a top view of a further variant of the valve member of Fig. 1 A;Figs. 5A and 5B illustrate cross-sectional and top views of a variant of the first valve member of Fig 1A; andFig. 6A and 6B illustrate perspective views of an analytical system including the valve assembly of Fig. 1A.Fig. 7 illustrates a cross-sectional view of a further variant of the valve members.SPECIFIC DESCRIPTION

[0021] Fig. 1A illustrates a disclosed valve assembly 100, comprising a holding member 110 with a stack of cylindrical members 102, 104 disposed inside the holding member 110. The holding member may be configured as a cage or have a cage-like configuration, for example. The stack of members 102, 104 are illustrated in Fig. 1B, and perspective views of each of the members, individually, are shown in Figs. 1C and 1 D respectively.

[0022] With reference to Fig. 1A, the valve assembly 100 comprises a first member 102 and a second member 104, held in a stack within a holding member 110. The holding member 110 is fixed to an analytical device or apparatus (e.g., a mass spectrometer) with attachment means 116, and the stack of members 102, 104 are accessible through the holding member 110 by a user, by a tool and / or by a mechanism, such that the first and / or the second members 102, 104 may be rotated to actuate the valve assembly 100. The mechanism may comprise a motor, which motor may be remotely controlled.

[0023] As best shown in Fig. 1 D, the first member 102 comprises a first face 112 and a second face 114, and through-bore 106 between the two faces 112, 114. The through-bore 106 is accessible through the holding member 110 such that a transfer line or a sample from another apparatus (e.g., from a gas chromatography column) can be inserted into the valve assembly 100 via the through-bore 106. Similarly, and with reference to Fig. 1 C, the second member 104 comprises a through-bore 108 (illustrated with dashed lines behind the first member 102) extending between a first face 122 and a second face (not visible) of the second member 104. The interface defined by the opposing first faces 112, 122 of the first and second members 102, 104 creates a seal between the members within the valve. The opposing first faces 112, 122 may be precisely ground and polished to improve sliding and sealing properties in the interface. For example, the faces 112, 122 may be polished to facilitate wringing and may, in some cases, in some cases, have an arithmetic average roughness of less than or equal to 1 microinch (0.025pm), and / or a flatness deviation of less than or equal to 5 microinches (0.13pm), as discussed above. Advantageously, the precisely ground and polished faces are polished sufficiently smooth to form a seal when placed on top one another, and to have reduced friction to facilitate the sliding motion between the faces. In the illustration of Fig. 1b, the through-bores 106, 108 of the first and second members 102, 104 are out of alignment, indicating a sealed state of the valve 100. The first member 102 and the second member 104 are cylindrical and aligned on top of one another in the stack, which allows one or both of the members to be slidably rotated within the holding member 110 to align the through-bores 106, 108 and enable a fluidic communication within the valve, thereby placing the valve in an ‘on’ state. Instead of the cage structure shown in Fig. 1A, the holding member 110 may be constituted by a railed mount, a recess with or without associated clamping members, or another suitable structure.

[0024] In an alternative arrangement, depicted in Figs. 2A to 2F, a valve assembly 200 is instead configured to facilitate actuation by a lateral sliding (linear) motion. With reference to Fig. 2A, a valve assembly 200 comprises a first member 202 and a second member 204 held within a holding member 210. The holding member 210 enables a lateral sliding motion of the first member 202 relative to the second member 204, as indicated by the arrow in Fig. 2B. The lateral sliding motion enables the respective through-bores 106 and 108 of the firstand second members 202, 204 to be brought in and out of alignment, thereby actuating the valve between the sealed state and the connected (or ‘on’) state. The holding member 210 may comprises an opening (not visible in the drawing) on one side which allows the first member 202 to be removed from and / or inserted into the holding member.

[0025] As illustrated in Figs. 2B, 2C, and 2D, the second member is an oblong disc (or stadium) shape, and the first member is a circular disc, such that the members remain in a supported stack during the lateral sliding motion of the first member across the first face of the second member, as described above. However, it will be appreciated that the members 202, 204 may actuate with arcuate sliding motion, and / or be the same or similar to the members 102, 104 of Fig. 1.

[0026] Figs. 3A and 3B depict cross-sectional and top views of a valve member 300 including two through-holes. The first through-hole is formed of an upper bore 310 and a lower bore 312. The upper bore 310 is formed at the second face 114 of the valve member 300, and comprises a tapered edge 308. The upper bore 310 is configured, i.e., shaped, to receive a sleeve of a transfer line of the analytical system, which is guided on entry to the upper bore 310 by the tapered edge 308. The lower bore 312 runs from the upper bore 310 to the lower face 112 of the valve member 300. The lower bore 312 has a narrower diameter than the upper bore 310, so as to receive and provide a feedthrough for the transfer line of the analytical system which may extend beyond the confines of the sleeve. The two bores 310 and 312 together nest the transfer line within the valve member 300 of the valve assembly 100, to hold or seal the transfer line in place during transfer of a sample therethrough. In particular, the two bores 310 and 312 may provide support and hold the transfer line to reduce the risk of breaking seal between the transfer line and the valve member, or breaking the vacuum of one or more apparatuses in the analytical system. The second through-hole of the valve member 300 comprises a single bore 306 which runs with a substantially constant diameter from the first face 112 to the second face 114 of the valve member 300. The diameter and the position of the bore 306 of the second through-hole is configured to correspond with the lower bore 312 of the first through-hole when two such valve members 300 are stacked in a connected configuration.

[0027] As best shown in Fig. 3C, the valve member 300 can be duplicated and stacked with an identical valve member 300 to form the valve assembly 100. Advantageously, by forming the valve assembly 100 from duplicate valve members 300, manufacturing of the valve assembly 100 components only requires manufacturing one form of universal valve member 300 (twice), thereby improving efficiency, saving on manufacturing costs, and facilitating easy component replacement. Additionally, even if the specifications of the through-holes for the first member 102 and the second member 104 differ (as in Fig. 3C), by providing both through-holes with different specifications on the universal valve member 300, the valveassembly 100 can be configured to provide fluidic communication through the necessary through-holes as required.

[0028] With continued reference to Fig. 3C, the rear valve member 300 (indicated with dotted lines) is flipped, such that the transfer-line-receiving bore hole 310 of the front valve member 300 may be positioned in fluidic communication with the bore 306 of the rear valve member 300. In this way, the bore 306 of the front valve member 300 may be largely obsolete. Nevertheless, the through hole 306 of the first member 300 may still be used, e.g., for alternative transfer lines and / or apparatuses.

[0029] It will be appreciated that the valve members of the valve assembly 100 or 200 may be configured in line with the shapes of the first and second through-holes of the valve member 300, providing one of the valve members, for example valve member 102, with a through-hole shaped like the first through hole and the other one, for example valve member 104, with a through-hole shaped like the second through-hole. While this arrangement requires the manufacture of two differently configured valve members, it retains the advantages of the individual through hole configurations to connect to the transfer line I analytical device.

[0030] Alignment features can be used to assist with the actuation of the valve assembly 100 into sealed states and / or into ‘on’ (that is, connected) states. In a specific arrangement, with reference to Figs. 4A and 4B, first and second members 402 and 404 include magnets 406, which are embedded within the respective members. The polarity and position of the magnets 406 are configured to facilitate placement of the valve members 402, 404 into one or more preferred states. In the illustrated magnetic configuration, magnets 406 are positioned with inverse polarities on opposite edges of each member 402, 404, such that the members are magnetically guided to the ‘on’ state, with the bore 312 of the first member 402 in alignment with the bore 306 of the second member 404. It will be appreciated that more magnets 406 or different magnetic configurations could be incorporated in the valve assembly 100, to similarly facilitate alignment of the valve in a ‘sealed’ state, or to additional ‘on’ states (e.g., if the first member 402 comprises more than one input through-hole). Alignment members to facilitate alignment into open and sealed states of the valve, in the form of magnets or otherwise, may be provided with any of the described valve member configurations.

[0031] As illustrated in Figs. 4A and 4B, providing two or more magnets 406 in each of the first and second members serves to provide multiple magnetic configurations. In particular, as illustrated in Fig. 4A, the magnets 406 may guide the first and second members 402, 404 to a good alignment in the ‘connected’ state, but may also repel or hinder an incorrect alignment when magnetic poles of the same polarity are brought together (in the case of Fig 4A, the incorrect / repelled alignment is 180 degrees from the shown configuration, i.e., withboth through-bores 306 aligned). This is particularly advantageous in examples where the first and second members 402, 404 are both provided with first and second through-bores 306, and / or where there (otherwise) exists an unwanted configuration of the valve members 402, 404.

[0032] In another example, and with reference to Fig. 4C, a plurality of magnets 406 are provided in multiple locations across each of the first and second members 402, 404. As such, the magnets may be configured / orientated: to facilitate alignment of the two members 402, 404 between two or more configurations; to facilitate rotational or linear movement of the members 402, 404 relative to one another; and / or to facilitate detachment of the members 402, 404. For example, as illustrated in Fig. 4C, a plurality of magnets 406 are provided in the first member 402 along the path traced by the relative movement between the first and second members 402, 404 during use (i.e., along a perimeter of the first member 404). As illustrated, the orientations of the magnets 406 in the first member 402 are configured such that the first and second members 402, 404, when stacked, may be guided to an ‘on’ state (i.e., at 0 degrees relative to the second member) and also guided to a ‘sealed’ state (i.e., at 90 degrees relative to the second member), when the members are moved near either state. Additionally or alternatively, the magnets 406 may be provided and orientated in the first and / or second member 402, 404 such that the members are configured to be repelled from an unwanted or incorrect configuration in the stack, and / or to be repelled from a location between the ‘on’ state and the ‘sealed’ state (e.g., at 30 and 60 degrees around the first member), that is, from a position in which a magnet 406 in the first member 402 faces a magnet 406 of the same polarity in the second member 404. The repulsion of the magnets 406 in this configuration may advantageously assist movement of the first and second members 402, 404 between configurations, and / or assist in their mutual detachment. In particular, magnets 406 may be provided and orientated to provide a ‘detachment configuration’, in which at least one magnet 406 of the first member 402 faces at least one other magnet 406 of the same polarity in the second member 404, thereby causing repulsion of the two members from each other. Thus, when the members are slidably moved into the detachment configuration, separation of the members from one another is facilitated by the repulsive magnetic force. Although fig. 4C illustrates 12 magnets around a perimeter of the first member 402, it will be appreciated that other numbers of magnets 406 and other locations for magnets are also considered and would be suitable for the above examples. For example, the first and second members 402, 404 may each have the same or different numbers of magnets, and / or may each comprise 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or more magnets 406. Additionally, the magnets 406 may be positioned and orientated in any suitable location within, on, or around the members 402, 404. Furthermore, magnetisable parts ormagnetic materials may be used in place of the magnets discussed above, insofar as they are used with at least one counterpart magnet on the opposing member.

[0033] Figs. 5A and 5B depict an alternative form of a first member 502, comprising a primary through-hole with bores 310 and 312. In addition, the first member 502 includes tributary channels 508 and 506, which extend from the second face 114 of the first member 502 into the through-hole 106. In this way, through-hole 106, tributary channel 508, and tributary channel 506, combine in the lower bore 312 of the valve assembly 100 prior to entry to a through hole of a second member (not shown in Figs. 5A or 5B). The additional channels 506 and 508 enable control gases or other injectants to be inserted into the valve assembly 100 and combined with the sample of the transfer line. The combined samples can then be inserted into the apparatus of the analytical system.

[0034] With reference to Fig. 6A, an analytical system 600 comprises a gas chromatography (GC) column, e.g., within chromatography device 602, and a mass spectrometry (MS) apparatus 608. A sample is transferred out of the GC column through a transfer line 604 and into an ion source 606 of the MS apparatus 608 via the valve assembly 100. As best shown in the enlarged and exploded diagram of Fig. 6B, the second member 204 of the valve assembly 100 is fixed in the wall of the ion source 606 or held (e.g. clamped) in a recess in the wall of the ion source, and the first member 202 is mounted upon the ion source 606 on a railed mount (not shown). The railed mount operates orthogonally to the through-bore 108 of the second member 204 and ion source 606, thereby enabling the first member 202 to slide back and forth against second member 204. The ion source 606 is under vacuum, thus the first member 202 is held or pressed against the first face of the second member 204, e.g., using a holding member or spring mechanism (not shown), so that the vacuum of the ion source 606 is not broken upon activation or deactivation of the valve assembly 100. The transfer line 604 is coupled to the first member 202 of the valve assembly 100, such that the sliding motion of the first member 202 may switch between a state of fluidic connection between the GC column and the ion source 606, and a sealed state.Naturally, it will be appreciated that any of the described valve configurations may be used in place of the members 202, 204, for example using members 102, 104 or 300, as described above. Additionally, in some examples, the first member 202 may be integral with, or directly attached to, the GC column and / or chromatography device 602. As a result, the chromatography device 602 can be connected to the mass spectrometry apparatus 608 directly and without the need for a transfer line 604.

[0035] Fig. 7 depicts a further arrangement of valve member, which may be, for example, an alternative or an addition to the arrangements of Figs. 1 A or 4A. In Fig. 7, a vacuum chamber is used to hold the valve members together. That is, the valve members 102 and 104 are each provided with a recess 132 and 142 respectively. The recesses are arranged insuch a way that they align when the valve members are brought together, so that the recesses 132 and 142 together constitute a single cavity. The cavities 132 and 142 may be arranged at the centre of the valve members, e.g., so that the recesses remain aligned upon rotational movement of the first and second members. It will be appreciated that it is not necessary to provide the recess in both members. For example, a recess 132 or 142 may be provided on the first surface of the first or of the second member, such that an internal cavity is defined by the recess 132 or 142 in contact with the (flat) surface of the adjacent member. An additional bore 143 is provided, which may be connected to a pump (not shown) to draw a vacuum in the cavities 132, 142. By providing an evacuated internal cavity, vacuum pressure may be used to facilitate a sealed mating between the surfaces of the members 102 and 104 during operation and to reduce differential pressures between sections of the members. Additionally or alternatively, when separating the first and second members, the internal cavity provided by recesses 132 and / or 142 may be pressurised, e.g., by a pump, thereby forcing the recesses 132, 142 apart and facilitating separation of, or reduced friction between, the first and second valve members. In particular, the force exerted by the cavity under pressure may reduce resistive or ‘sticking’ force acting between the members and allow the members to be rotated or laterally shifted more easily. In this way, the internal cavity may facilitate sealing, may facilitate movement of the first and second members, and / or may facilitate separation of the first and second members.

[0036] In addition to GC-MS (gas chromatography mass spectrometry), the invention can be used in LC-MS (liquid chromatography mass spectrometry), LC-OES (liquid chromatography optical emission spectrometry), IC-MS (ion chromatography mass spectrometry) and IC-OES (ion chromatography optical emission spectrometry).

[0037] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other implementations will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to specific example implementations, it will be recognized that the disclosure is not limited to the implementations described but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

CLAIMS1. A valve assembly for use with an analytical system, the valve assembly comprising first and second members, each defining a through-bore from a first face to a second face of each member, the first and second members being stacked together with their first faces in contact to form a seal between the members, one of the first and second members being slidably movable relative to the other between a first configuration in which the through-bores are fluidically connected and a second configuration in which the through-bores are sealed from each other.

2. The valve assembly of any preceding claim, wherein the members are formed of ceramic material.

3. The valve assembly of claim 2, wherein the first face of each member is polished to enable wringing of the members, optionally wherein the surface has an arithmetic average roughness of less than or equal to 0.025pm, and / or a flatness deviation of less than or equal to 0.13pm.

4. The valve assembly of any preceding claim, wherein slidable movement of the members to dispose the stack in at least two configurations is rotational or linear movement5. The valve assembly of any preceding claim, wherein the members are cylindrical.

6. The valve assembly of any preceding claim, further comprising a holding member configured to hold the stack of members.

7. The valve assembly of any preceding claim, wherein the first member and the second member are of substantially identical shape.

8. The valve assembly of claim 7, wherein the first and second members each have first and second through-bores, the first through-bore configured differently from the second one.

9. The valve assembly of any preceding claim, wherein the through-bore in the first member is of a first shape comprising a first bore at the first face for receiving a transfer line of a chromatography system and a second bore, wider than the first bore, at the second face for receiving a sleeve of the transfer line.

10. The valve assembly of claim 9, wherein the through-bore has a tapered end at the second face of the first member.

11. The valve assembly of any preceding claim, wherein the through-bore in the second member is of a second shape comprising a constant bore corresponding with a bore of the through-bore in the first member at the first face.

12. The valve assembly of claim 9 or 10, wherein the through-bore in the second member is of a second shape comprising a constant bore corresponding with a bore of the through- bore in the first member at the first face, and each member defines a through-bore of the first shape and a through-bore of the second shape.

13. The valve assembly of any preceding claim, wherein the first member further comprises at least one channel connecting the through-bore of the first member to an additional opening in the first member.

14. The valve assembly of any preceding claim, further comprising at least one magnet disposed in one or each member, wherein the magnet or magnets define at least one of the configurations.

15. The valve assembly of any preceding claim, further comprising at least one magnet disposed in each member, wherein the magnets are orientated relative to each other to repel one another when aligned in the stack.

16. The valve assembly of any preceding claims, wherein the first face of one or both valve members further comprises a recess configured to: a.) constitute a vacuum cavity in co-operation with the opposing valve member; and / or b.) constitute a cavity adapted to be pressurised.

17. A chromatography transfer line coupled to a valve assembly according to any of the preceding claims.

18. An analytical system comprising one or more analytical devices, at least one of the analytical devices comprising the valve assembly of any of claims 1 to 15 to selectively open and close a fluid port of the analytical device.

19. The analytical system of claim 18, wherein the analytical system is a gas chromatography - mass spectrometry system comprising a gas chromatography device connected via a transfer line and the valve assembly to a mass spectrometry device.

20. The analytical system of claim 19, wherein the second member is fixed to the mass spectrometry device.

21. The analytical system of claim 17 or 18, wherein the through-bore of the second member is in fluidic connection to an ion source of the mass spectrometry device.

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