Airlock assembly for an analytical system

Abstract

An airlock assembly for injecting fluid into an analytic system comprises a stack of a first member, a second member, and a third member in between the first and second member. Each member comprises two opposing faces and a chamber is disposed between respective openings in the opposing faces. Adjacent faces of adjacent members face each other to form a seal, and adjacent members are slidably movable relative to each other to dispose the stack in at least two configurations. A first configuration connects the chamber in the first member in fluidic communication with the chamber in third member and seals an opening of the chamber in the second member with the third member. A second configuration connects the chamber of the third member in fluidic communication with the chamber of the second member and seals an opening of the chamber of the first member with the third member.

Description

AIRLOCK ASSEMBLY FOR AN ANALYTICAL SYSTEMTECHNICAL FIELD

[0001] This disclosure relates to an airlock assembly for an analytical system, in particular although not exclusively in the context of injectors for gas chromatography apparatuses.BACKGROUND

[0002] Gas chromatography (GC) systems and other analytical systems may include an injector, such as a programmable temperature vaporizer (PTV) inlet or a split / split-less (SSL) inlet. A sample of interest may be introduced into the analytical system, e.g., into a GC column, via the injector, for sample analysis. In some known arrangements, the injector may include a septum comprising a soft elastomeric material through which a needle is inserted and a sample injected for introduction into the system.

[0003] However, there are various technical challenges and considerations associated with the injectors of such analytical systems, because it is generally desirable to achieve consistent, reliable and reproducible experimental results, whilst providing efficient injection means which are convenient to use. For example, some experiments may require a precise and controlled sample introduction, including maintaining or regulating pressure and temperature within the injector and the apparatus and minimising contamination of the sample. Elastomeric septa, for example, can age and fatigue leading to imperfect seals, loss of pressure and potential contamination if not replaced regularly. They can also cause ingress of septum material into the system as the septum is pierced.SUMMARY

[0004] Various and conflicting technical requirements associated with an analytical system may be addressed by providing an airlock assembly for an apparatus of an analytical system, such as for an injector of an analytical system. The airlock assembly can slide between a first configuration and a second configuration. The first configuration enables fluidic communication into a central chamber of the airlock assembly, whilst sealing the central chamber from the apparatus. Conversely, the second configuration enables fluidic communication between the central chamber of the assembly and the apparatus, whilst sealing the central chamber from the exterior of the analytical system. The airlock assembly may advantageously remove the requirement for pierceable septa and may therefore improve the durability of the injector.

[0005] With that in mind, the present disclosure relates to an airlock assembly for injecting a sample, e.g., a fluid, into an analytic system. The airlock assembly comprises a stack of a first member, a second member and a third member, with the third member positioned in-between the first and second members. Each member comprises two opposing faces and a chamber or through-bore disposed between respective openings in the opposing faces. The members are stacked such that adjacent faces of adjacent members in the stack face each other and form a seal at the interface between the adjacent members. For example, adjacent faces of adjacent members may be positioned flat against each other to form a seal. Additionally or alternatively, the seal may be provided with an O-ring, a gasket, or by another method known in the art.

[0006] Within the stack, the first and third member are slidably movable relative to each other and the second and third member are slidably movable relative to each other. The relative slidable movement of at least one of the members can be achieved by a tool, an actuator of the assembly, or by a user, to dispose the assembly in, and switch in sequence between, at least two configurations.

[0007] In a first configuration of the airlock assembly, the chamber in the first member is connected in fluidic communication with the chamber in third member, and an opening of the chamber in the second member is sealed with the third member (e.g., the opening of the second member is sealed by the face of the adjacent third member). In this way, a sample may be inserted, by user or by tool, into the chamber of the first member and may then pass into the chamber of the third member. The sample may be a liquid, a solid, or a gas. In a second configuration of the airlock assembly, an opening of the chamber of the first member is sealed from the third member and, the chamber of the third member is connected in fluidic communication with the chamber of the second member. In this way, the second configuration enables a sample to pass from within the third member into the analytical apparatus.

[0008] It will be appreciated that there are various ways to configure the stack of members to enable the relative movement to dispose the assembly into the two configurations defined above. In some examples, the third member may be slidably movable to select between the at least two configurations whilst the first member is in the same configuration relative to the second member in each configuration. In this way, movement of the third member alone may be sufficient to switch between the two configurations, since the third member is positioned between the other two members. In other words, if the chambers of the first and second members are out of alignment with each other, the third member may switch between fluidic connection with one member whilst sealing the other member, thereby operating the airlock assembly whilst only requiring the movement of the third member. Advantageously, this may allow both of the first and second members to be fixed or brazed to a cage or to the analytical apparatus, to improve stability and / or convenience.

[0009] In other examples, any two, or all, of the members are each slidable moveable. In particular, the first and / or second members may each be slidably moveable relative to thethird member to select between the at least two configurations. In any case, the airlock assembly is configured to enable access for a tool, a user, or an actuator, to cause slidable movement of the one or more slidable members as necessary.

[0010] By using a slidable movement of the members to achieve the two configurations, the airlock assembly is quick and easy to use, and does not require significant force or strain on the components as is otherwise common in known systems, for example, when piercing needles through a soft septum of an injector. Instead, the slidable movement of the members enables a smooth switching between the configurations, 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 sliding members may slightly wear over time to better fit one another. To strengthen the seal, force may be applied to applied between the components using magnetic, pneumatic, or other common means, such as a clamp or spring. 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.

[0011] At least one of the members may be substantially formed of ceramic material. A ceramic member may have properties advantageous to the analytical system, such as thermal insulation to reduce heat sinking during operation. In addition, the faces of each member may be precisely ground and polished ceramic, to facilitate a vacuum seal between the first faces of the members when they are in contact with one another. It will be appreciated that the members may be formed of precisely ground and polished metal components and / or of ceramic-coated components instead of being entirely formed of ceramic.

[0012] In some examples, the opposing surfaces of at least any two adjacent members may comprise a polished surface having an average arithmetic roughness (that is, the arithmetic average of the absolute deviation 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 them. In other words, the members with polished surfaces may adhere to each other in the same manner as gauge blocks or slip gauges. In some examples, 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 opposing faces of adjacent members, allow for sufficient molecular attraction and / or surface tension between the respective members in a stack to effectively bond the surfaces when slid together under pressure. In other words, theabove surface requirements facilitate effective wringing between adjacent members in the stack, which advantageously improves sealing.

[0013] Additionally, extended use of the polished surfaces (i.e., with surface conditions as described above) may further improve the seal and / or the ease of user manipulation, because the respective surfaces may become smoother with use or otherwise better tailored to one another so as to more easily slide between configurations.

[0014] In some examples, the airlock assembly comprises a holding member, such as a cage or recess, configured to hold the stack of members. The holding member supports one or more the members, and may be of any suitable form, such as a closed cage with an opening to enable access and utilization of the airlock assembly, or a cage which is open on one side to enable ease of access and to provide an aperture for slotting one or all of the members into the cage. 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 adjacent members.

[0015] The third member, the first and third members and / or the second and third members may be configured to move linearly or rotationally, e.g., within an aperture of the cage or constrained by a spindle about which the members can rotate. In either case, the members are accessible by a user or by a tool, and the airlock assembly may therefore be operated by a user or remotely / automatically, e.g., by an actuator comprised in the assembly. The members may be substantially cylindrical to facilitate a compact assembly and ease of use, particularly if the respective slidable movement of the members is rotational.

[0016] In some examples, the first, second, and / or third member comprise features to facilitate alignment of the components. In other words, alignment features may facilitate substantial alignment of the openings of adjacent faces within the stack of members, to position the airlock assembly in one or more of the respective airlock configurations. In particular, the airlock may comprise one or more magnets disposed in each of the members, e.g., such that the magnets define at least one of the configurations of the airlock. The configuration of the magnets guides an alignment of the two members into one or more of the configurations of the airlock, e.g., by providing opposite I same poles in respective portions of the members to magnetically attract I repel the members to the aligned position. For example, magnets may be provided and orientated such that adjacent members are repelled from an unwanted configuration and guided to one or more preferred configurations. In some further examples, two or more magnets may be provided in at least any two adjacent members, and may be configured to facilitate alignment into more than one different configuration. Each of the members for facilitating alignment may comprise at least one magnet, for example at least 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , or 12 magnets. Furthermore, in any of the examples relating to magnetic attraction as discussed herein, a magnetic ormagnetizable part may be used in place of a magnet in one of the adjacent members. For example, a magnetic part in one member may be magnetically attracted to a counterpart magnet in an adjacent member, thereby guiding an alignment of adjacent 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. Additionally, alignment members to facilitate alignment into the various open and sealed states of the airlock assembly, in the form of magnets or otherwise, may be provided with any of the described airlock assembly configurations.

[0017] In some examples, magnets are provided in at least any two adjacent members, and are orientated to provide a repulsive force when aligned (i.e. , due to the same poles facing one another). For example, the repulsion of the magnets may counter the frictional or ‘sticking’ force acting between adjacent members and therefore may assist relative movement of the adjacent members, and / or may assist in their mutual detachment. In particular, magnets may be provided and orientated to provide a ‘detachment configuration’, in which a magnet of the third member faces another magnet of the same polarity in the first and / or second member, thereby causing repulsion of the respective members from each other. Thus, when a member is slidably moved into a detachment configuration, separation of the member from the stack is facilitated.

[0018] The chamber of the first member may comprise a tapered opening, to facilitate fluid injection into the first member. Furthermore, in some examples, the airlock assembly further comprises a third configuration, in which the chamber in the third member is isolated from both the respective chambers in the first and second members. The third configuration may therefore allow for a temporary storage of the sample within the sealed central chamber of the airlock assembly prior to introduction of the sample into the analytical apparatus, which can facilitate, for example, the introduction of the sample at a desired time.

[0019] The second or third member may include one or more subsidiary channels connecting the chamber of the third member to an additional opening on the third member, for example a channel extending laterally from the chamber to an opening on a side wall of the member. However, other arrangements with additional channels or openings are also considered. In particular, an additional channel may advantageously act as a vent, in particular for split-type injection. For example, the airlock assembly may be heated whilst a sample is situated in the chamber of the third member, such that the sample can be separated by evaporation through the vent. In this way, the airlock assembly may simulatethe “split” mode of a split-splitless injector, with an additional channel to vent out unwanted material prior to introduction of the sample into the apparatus.

[0020] Additionally or alternatively, any of the members, preferably the third member, can include multiple chambers each provided with alternative dimensions or an alternative arrangement of openings or channels. In this way, and due to the relative sliding movement of the stack of members, the airlock assembly can be disposed in more than two configurations, i.e. , a plurality of configurations corresponding to each of the multiple chambers in each of the respective members. The multiple chambers may therefore allow for different ‘modes’ of operation without a need to change the airlock assembly, improving versatility and convenience. For example, the airlock assembly can be operated to switch, in sequence, between two desired configurations (i.e., between the desired chambers for use) to simulate an injector type or a combination of injector types, such as a split-splitless inlet, a PTV inlet, a thermal desorption inlet, and / or other column inlets known in the art.

[0021] The disclosure also relates to an analytic device, such as a Gas Chromatography apparatus, comprising the airlock assembly as described above. In particular, the second member of the airlock is secured to the analytic device to provide fluidic communication between the chamber in the second member and the analytic 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. The gas chromatography assembly may include a heater configured to heat a sample being injected or stored in the third member of the airlock assembly. For example, the third member may be positioned in thermal contact with at least a portion of the analytical device where a heater is stored.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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. 1 illustrates the body of an injector of an analytical system;Figs. 2Aa and 2B illustrate perspective and side views of the injector body of Fig. 1 comprising an airlock assembly for introducing a sample;Figs. 3A and 3B illustrate perspective views of two configurations, respectively, during operation of the airlock assembly of Fig. 2; andFig. 4 illustrates an exploded diagram of an airlock assembly.SPECIFIC DESCRIPTION

[0023] Fig 1. depicts an injector body 20 of a gas chromatography system with a through- opening 21 extending from a top surface to a bottom surface. The injector body 20 isconfigured to receive a sample through the through-opening 21 at the top surface of the injector body 20. With reference to Figs. 2A and 2B, an airlock assembly 10 is coupled to the top surface of the injector body 20 at the through-opening 21. The bottom surface of the injector body 20 is fluidly coupled to a GC column (not shown) of the GC system such that the sample may travel through the injector body 20 and into the GC column, where the sample may separate into its individual components.

[0024] As best shown in Fig. 4, the airlock assembly 10 consists of three members 11, 12, and 13 which each comprise an upper face 41 and a lower face 42, and at least one through- bore or chamber 51 , 52, 53 extending therebetween. The airlock assembly 10 is configured to enable a relative sliding motion between the members 51 , 52, 53 within the stack, and to enable alignment of adjacent through-bores (e.g., through-bores 51 and 53 or through-bores 52 and 53) of corresponding adjacent members within the stack. In this way, the relative sliding motion may dispose adjacent through-bores in fluidic communication with one another, as described below with reference to Figs. 3A and 3B.

[0025] Fig. 4 depicts the three members 11 , 12, 13 arranged as a contiguous stack of cylindrical discs centred around a central axis 40. However, it will be appreciated that non- cylindrical shapes of the members are also possible. Additionally, the members 11, 12, 13 may be of substantially the same form, e.g., to simplify or homogenise manufacturing methods and minimise costs, or alternatively the members may have differing dimensions and / or different arrangements of through-hole. For example, the third member 13 may be of a different shape and / or thickness to the first member 11 , e.g., to allow for a larger sample storage volume within the third chamber 53.

[0026] With continued reference to Fig. 4, the third member 53 comprises two distinct chambers 53 and 54 which can be used interchangeably to provide two different modes of the airlock assembly. Chamber 53 is sealed between openings in the respective faces, whereas chamber 54 includes a subsidiary channel 55, which extends from the chamber 54 to a side portion of the third member 13. The channel 55 may act as a vent, such that when a sample 31 (liquid or solid) is dispensed and sealed in the chamber 54, the sample 31 may be heated by a heater (not shown) of the analytical system to separate the sample by evaporation through the channel 55. In this way, chamber 54 ‘splits’ the sample 31 , discarding evaporated matter and allowing a remaining portion of the sample to be introduced into the system (e.g., by using one or more flow meters to measure a split ratio and determine a desired concentration of sample to be introduced into the system).Chambers 53 and 54 may therefore offer a ‘sealed’ and an ‘evaporation’ mode, respectively. It will be appreciated that other combinations of chambers or channels (to offer further modes) are also considered, by providing additional chambers or channels to one or more of the members 11 , 12, 13, in a similar manner as discussed herein alongside the sample. Forexample, additional chambers and channels could be added to enable additional inputs into the airlock assembly, such as a mobile phase, a control, or a carrier gas, which may be injected or introduced alongside the sample. For example, in Fig. 4, an optional additional channel 59 is shown to be arranged in the second member 12. This additional channel 59 may be connected to a gas source, optionally by way of a pressure regulator. The gas pressure in the additional channel 59 may be higher than the gas pressure in the column of the GC system.

[0027] Other shapes of through-bores or chambers are also possible. For example, as shown in Fig. 4, the chamber 51 in the first member 11 is tapered, to guide in a needle or vial or other tool and thus to facilitate a more accurate placement of the sample into the first chamber 51. The members 11, 12, 13 may have any suitable shape, and may be mounted relative to each other for any suitable sliding motion, for example rotational sliding about a centred or off-centred axis or translational sliding.

[0028] Figs. 3A and 3B illustrate the airlock assembly in two different configurations, respectively, for the introduction of a sample into the injector body 20. In the first configuration, illustrated in Fig. 3A, a sample 31 is transferred, via an ampoule, a syringe, or a needle 30, into the chamber 51 of the first member 11. The chambers 51 and 53 of the first and third members 11 and 13 are aligned or otherwise disposed in fluidic communication and chambers 52 and 53 are not, to prevent fluidic communication between them (defining the first configuration). With chambers 51 and 53 of first and third members 11 , 13 in fluidic communication, the sample 31 can pass into the chamber 53 of the third member 13. Additionally, as illustrated in Fig. 3A, the chamber 52 of the second member 12 is not in fluidic communication with the respective chamber of the third member 13, because the chamber 53 of third member 13 is sealed by the upper face 41 of the second member 12. Therefore, the sample remains in the third chamber 53.

[0029] With that in mind and turning now to Fig. 3B, the third member 13 is slid with respect to the first and second members 11, 12 such that the chamber 53 is sealed by the lower face 42 of the first member 11. In so doing, a third intermediate configuration (not shown) that exists between the illustrations of Figs. 3a and 3b is possible, in which the sample 31 is sealed within the third chamber 53 of the airlock assembly 10 by the respective faces of the adjacent members on either side of the chamber. To dispose the stack in the second configuration as illustrated in Fig 3b, the third member 12 is slid within the stack to dispose the second chamber 52 in fluidic communication with the third chamber 53, such that gravity allows the sample to pass through into the second member 12. The second member 12 is placed in fluidic communication with the through-opening 21 of the injector body 20, such that the sample 31 passes into the analytical system.

[0030] It will be appreciated that whilst rotational movement is implied between Figs. 3a and 3b, the movement may additionally or alternatively be linear or arcuate. Furthermore, whilst Fig. 3a and 3b imply movement of the third member 13 only, it will be appreciated that the first and second members 11 and 12 may similarly be slid to achieve the two (or three) configurations of the airlock assembly. In such examples (not shown), the second member12 may be only partially arranged within the injector body 20, so that it is accessible by a user or tool.

[0031] With reference to Figs 2A and 2B, the second member 12 of the airlock assembly 10 is typically arranged in the body of the injector 20, while the first and third members 11 and13 extend above the injector body 20, which may increase the thermostability of the second member 12, e.g., to avoid condensation of the vapourised sample. Alternatively, in some arrangements, the entire stack extends above the injector body 20. In some examples, and as illustrated in Figs. 2A and 2B, the second member 12 is secured, for example brazed, glued, welded or clamped to, or integral with, the injector body 20.

[0032] 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. For example, the airlock assembly discussed herein may be implemented with gas, liquid, or solid samples, and with any suitable analytical device, such as a mass spectrometer, gas spectrometer, optical spectrometer, or other suitable instrument known in the art. 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

CLAIMS:

1. An airlock assembly for injecting fluid into an analytic system, the airlock assembly comprising a stack of: a first member; a second member; and a third member in between the first and second member; wherein each member comprises two opposing faces and a chamber disposed between respective openings in the opposing faces; wherein adjacent faces of adjacent members in the stack face each other to form a seal; and wherein the first and third member are slidably movable relative to each other and the second and third member are slidably movable relative to each other, to dispose the stack in at least two configurations comprising: a first configuration, connecting the chamber in the first member in fluidic communication with the chamber in third member and sealing an opening of the chamber in the second member with the third member, and a second configuration, connecting the chamber of the third member in fluidic communication with the chamber of the second member and sealing an opening of the chamber of the first member with the third member.

2. The airlock assembly of claim 1 , wherein the adjacent faces of adjacent members are positioned flat against each other to form a seal.

3. The airlock assembly of claim 2, wherein members are formed of ceramic material.

4. The airlock assembly of claim 3, wherein the adjacent faces of the adjacent members are polished to enable wringing of the members, optionally wherein the adjacent faces have 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.

5. The airlock assembly of any preceding claim, wherein the members are cylindrical.

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

7. The airlock assembly of any preceding claim, wherein the stack is configured for rotational movement of one or both of the first and third member relative to the second member.

8. The airlock assembly of any preceding claim, wherein the stack is configured for linear movement of one or both of the first and third member relative to the second member.

9. The airlock assembly of any preceding claim, wherein the third member is slidably movable to select between the at least two configurations and the first member is in the same configuration relative to the second member in the at least two configurations.

10. The airlock assembly of any of claims 1 to 8, wherein the first and second members are each slidably moveable relative to the third member to select between the at least two configurations.

11. The airlock assembly of any preceding claim, wherein the chamber in the first member comprises a tapered opening.

12. The airlock assembly of any preceding claim, further comprising a third configuration, in which the chamber in the third member is isolated from both the respective chambers in the first and second members;13. The airlock assembly of claim 12, wherein the third member further comprises a channel connecting the chamber of the third member to an additional opening on the third member.

14. The airlock assembly of any preceding claim, further comprising at least one magnet disposed in one of, a pair of or each of the first, second and third members, wherein the magnet or magnets define at least one of the configurations.

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

16. An analytic device comprising the airlock assembly of any preceding claim, wherein the second member is secured to the analytic device to provide fluidic communication between the chamber in the second member and the analytic device.

17. The analytic device of claim 16, wherein the analytic device comprises a gas chromatography apparatus.

18. The analytic device of claim 17, wherein the analytic device comprises a heater configured to heat the airlock assembly.

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