Analytical instrument

Abstract

An analytical instrument such as a liquid chromatography (LC) stack comprises a frame and an analyser such as a mass spectrometer (MS) which is configured to be installed within a main body of the frame. The analyser has one or more vacuum chambers, and the instrument further comprises a vacuum line configured to provide a vacuum connection between the vacuum chamber(s) of the analyser and a vacuum pump. The analyser and the frame are configured such that the analyser can be slidably moved between a first position in which the analyser is installed within the main body of the frame and a second position in which the analyser is at least partially removed from the main body of the frame. The vacuum line is configured such that the vacuum connection between the vacuum chamber(s) of the analyser and the vacuum pump can be maintained when the analyser is in the first position, when the analyser is in the second position, and when the analyser is between the first position and the second position.

Description

[0001] Analytical instrument

[0002] Field of the invention

[0003] The present invention relates to analytical instruments, particularly liquid chromatography-mass spectrometry (LC-MS) systems.

[0004] Background

[0005] Liquid chromatography (LC) is a widely used separation technique in analytical chemistry that involves the separation of mixtures based on their interactions with a stationary phase and a mobile phase.

[0006] One purpose of liquid chromatography is the separation of analytes of interest from a sample being commonly embedded in a complex matrix. One non-limiting example of such LC separation is the detection of metabolites of target analytes in blood plasma.

[0007] LC separation can provide enhanced reliability of analytical chemistry analysis because in addition to the specific detection of the target analytes by a mass analyser the chromatographic retention time provides an independent attribute confirming the identities of the target analytes.

[0008] A typical liquid chromatography instrument comprises several components, including a solvent delivery system, a sample injector, a chromatographic column, and an analyser. These components are commonly arranged together in a “stack” configuration, i.e. to form a so-called liquid chromatography stack. There are several types of analysers used in liquid chromatography stacks, including UV detectors and fluorescence detectors.

[0009] Although it is common to interface liquid chromatography instruments with mass spectrometers, this is normally done in a way in which the mass spectrometer remains separate from the liquid chromatography stack. More recently however, reduced-sized mass spectrometers have been developed for use as the analyser within a liquid chromatography stack. Mass spectrometers require vacuum conditions and are normally connected to one or more vacuum pumps during operation.

[0010] It is believed that there remains scope for improvements to analytical instruments. Summary

[0011] A first aspect provides an analytical instrument comprising: a frame; an analyser having one or more vacuum chambers, wherein the analyser is configured to be installed within a main body of the frame; and a vacuum line configured to provide a vacuum connection between the vacuum chamber(s) of the analyser and a vacuum pump; wherein the analyser and the frame are configured such that the analyser is slidably movable between a first position in which the analyser is installed within the main body of the frame and a second position in which the analyser is at least partially removed from the main body of the frame; and wherein the vacuum line is configured such that the vacuum connection between the vacuum chamber(s) of the analyser and the vacuum pump can be maintained when the analyser is in the first position, when the analyser is in the second position, and when the analyser is between the first position and the second position.

[0012] Embodiments provide an analytical instrument (such as a liquid chromatography (LC) instrument) that includes a frame (e.g. of a housing), an analyser (such as a mass spectrometer) with one or more vacuum chambers, and a vacuum line for connecting the vacuum chamber(s) of the analyser to a vacuum pump. The instrument is designed to allow the analyser to be at least partially (or fully) removed from a main body of the frame (e.g. from a main body of the housing), while still maintaining the vacuum connection between the vacuum chamber(s) and the vacuum pump.

[0013] In particular embodiments, the analyser and the frame are configured so that the analyser can slide between a fully installed (first) position within the main body of the frame and a second position in which the analyser is at least partially (or fully) removed from the main body of the frame. In other words, the analyser and the frame may be configured such that the analyser is slidably movable from a closed arrangement (first position) in which the analyser is installed within the main body, to an open arrangement (second position) in which the analyser is moved from the main body of the frame. The analyser may be arranged in the first position during use and may be moved to the second position for maintenance, for example. The vacuum line is designed to maintain the vacuum during this sliding movement, e.g. by virtue of a flexible tube (i.e. a hose) and / or a telescopic arrangement of a first rigid pipe and a second rigid pipe. In other words, the vacuum line is configured such that the vacuum connection between the vacuum chamber(s) of the analyser and the vacuum pump can be maintained when the analyser is configured in the closed arrangement, when the analyser is configured in the open arrangement, and when the analyser is at any position between the closed arrangement and the open arrangement.

[0014] In some embodiments, the first and second rigid pipes are configured to move relative to each other along a common axis, allowing the vacuum line to be compressed or extended. The first rigid pipe may have a larger inner diameter than the outer diameter of the second rigid pipe, and the second rigid pipe may be arranged at least partially within the first rigid pipe in a coaxial manner. This telescopic arrangement allows the vacuum line to be compressed when the analyser is fully installed within the main body of the frame and extended when the analyser is at least partially (or fully) removed from the main body of the frame.

[0015] In some embodiments, the first and second pipes are connected (i.e. sealed) by a pneumatic or hydraulic rod seal.

[0016] In some embodiments, the first and second pipes are connected (i.e. sealed) by a flexible tube. Both the first and second rigid pipes may have respective inlets and outlets, and the flexible tube may connect the outlet of the first rigid pipe to the inlet of the second rigid pipe. The flexible tube may run from the outlet of the first rigid pipe against the inner wall of the first rigid pipe, then turn at a turning point and run against the outer wall of the second rigid pipe to or close to the outlet of the second rigid pipe. In this way, most of the flexible tube may be supported by the inner wall of the first rigid pipe and / or by the outer wall of the second rigid pipe, and only the turning point of the flexible tube is unsupported by one of the rigid pipes.

[0017] The vacuum line may be configured such that, when the first and second rigid pipes are moved between the compressed state and the extended state (and / or when the analyser is moved between the first and second positions), the lengths of the parts of the tube supported by the first and second pipes change, while the length of the unsupported turning point remains substantially the same. Part of the flexible tube may be transferred from the inner wall of the first rigid pipe to the outer wall of the second rigid pipe (or from the outer wall of the second rigid pipe to the inner wall of the first rigid pipe) in a rolling manner.

[0018] In some embodiments, the flexible tube may have a constant inner diameter that corresponds to the outer diameter of the first rigid pipe and the flexible tube may be connected to the outlet of the first rigid pipe and to a fitting arranged on or close to the outlet of the second rigid pipe. The fitting may have a radially undulating profile, such that its perimeter corresponds to the inner diameter of the flexible tube. For example, the fitting may be shaped like a gear with round teeth.

[0019] In some embodiments, the instrument includes a vacuum pump that is connected to the vacuum line and is responsible for maintaining the vacuum chamber(s) of the analyser under vacuum. The vacuum line is specifically designed to ensure that the vacuum connection can be maintained even when the analyser is partially (or fully) removed from the main body of the frame.

[0020] In some embodiments, the instrument further comprises a fore vacuum pump and a turbomolecular pump. The one or more vacuum chambers may comprise a series of two or more vacuum chambers, including a fore vacuum chamber and one or more further vacuum chambers. The turbomolecular pump may be configured to pump the one or more further vacuum chambers, and the fore vacuum pump may be configured to pump the fore vacuum chamber and to pump an output of the turbomolecular pump.

[0021] The vacuum line may be configured such that the fore vacuum pump and the turbomolecular pump can together maintain the vacuum chambers of the analyser under vacuum when the analyser is in the first position, when the analyser is in the second position, and when the analyser is between the first position and the second position.

[0022] The turbomolecular pump may be, together with the analyser, slidably movable between the first position and the second position. The vacuum line may be configured to provide a vacuum connection between (i) the turbomolecular pump and / or the fore vacuum chamber of the analyser, and (ii) the fore vacuum pump.

[0023] In general, the instrument may be a chromatography instrument, such as a liquid chromatography (LC) stack, a gas chromatography (GC) stack, an ion chromatography (IC) stack, or similar. The analyser may be a mass spectrometer, e.g. of a type comprising an electrostatic ion trap mass analyser. The instrument may further comprise one or more further analyser(s), such as any one or more or each of a UV detector, a fluorescence detector, a charged aerosol detector.

[0024] It will be appreciated that this analytical instrument provides a user-friendly and easily maintainable solution. The telescopic arrangement of the vacuum line allows for easy removal of the analyser from the main body of the frame without compromising the vacuum connection, and the design of the vacuum line supports the necessary movement and flexibility. Description of the drawings

[0025] Various embodiments will now be described in more detail with reference to the accompanying Figures, in which:

[0026] Figure 1A shows schematically a liquid chromatography stack in accordance with embodiments, and Figure 1 B shows schematically a liquid chromatography stack in accordance with embodiments;

[0027] Figure 2A shows schematically an outer view of a vacuum line in a retracted state in accordance with embodiments, Figure 2B shows schematically a cross section of a vacuum line in the retracted state in accordance with embodiments, and Figure 2C shows schematically a cross section of a vacuum line in an extended state in accordance with embodiments;

[0028] Figure 3A shows schematically detail of a membrane connection of a vacuum line in accordance with embodiments, and Figure 3B shows schematically detail of a membrane of a vacuum line in accordance with embodiments;

[0029] Figure 4 shows schematically an analytical instrument in accordance with embodiments;

[0030] Figure 5A shows a perspective view of an analytical instrument in a closed position in accordance with embodiments, Figure 5B shows a perspective view of an analytical instrument in an open position in accordance with embodiments, Figure 5C shows a side view an analytical instrument in a closed position in accordance with embodiments, and Figure 5D shows a side view an analytical instrument in an open position in accordance with embodiments; and

[0031] Figure 6 shows a perspective view of an analytical instrument in accordance with embodiments.

[0032] Detailed description

[0033] A liquid chromatography stack is a combination of various components used for liquid chromatography analysis. These various components are arranged together in a frame and / or housing in a “stack” configuration, i.e. to form a so-called liquid chromatography stack.

[0034] Figures 1A and 1 B show schematically a liquid chromatography stack in accordance with embodiments. As shown in Figures 1A and 1 B, the stack includes a solvent delivery system 10, which is responsible for pumping and delivering the mobile phase or solvent to the chromatographic column 30. This system may include a solvent reservoir, pumps, and a mixing chamber to ensure a consistent and controlled flow of the mobile phase.

[0035] The stack also includes a sample injector 20, which is used to introduce the sample into the chromatographic system. The sample injector may allow for precise and reproducible injection of the sample, ensuring accurate separation and detection.

[0036] The stack also includes a chromatographic column 30. The column may be packed with a stationary phase, which interacts with the sample components to separate them based on their affinity and interaction with the stationary phase. The column can be of various types, such as reversed-phase, normal phase, ion-exchange, or size-exclusion, depending on the separation requirements.

[0037] Finally, the stack includes an analyser 40, which is used to detect and quantify the separated sample components.

[0038] In addition to the illustrated core components, the liquid chromatography stack may also include other components and accessories such as a degasser to remove dissolved gases from the mobile phase, a column oven to control the temperature of the column, a data acquisition system and / or a control system, and so on.

[0039] In the present embodiment, the analyser 40 is a “miniature” mass spectrometer that is configured to be installed within the LC stack. The mass spectrometer may have any suitable design. In particular embodiments, the mass spectrometer includes an electrostatic ion trap mass analyser, such as an Orbitrap™ mass analyser. The mass spectrometer requires high vacuum conditions during operation and is therefore connected to a vacuum pump 50 via a vacuum line 60.

[0040] As illustrated by Figures 1A and 1 B, the analyser 40 and the frame are configured such that the analyser is at least partially slidably removable from the main body of the frame, for example for maintenance. Figure 1 A shows the analyser 40 when it is fully installed within the frame, and Figure 1B shows the analyser 40 when it has been slid out from the frame. It can be desirable to maintain the analyser 40 under vacuum conditions both when the analyser is installed within the frame and when it is being slid out from the frame. This can reduce down-time of the instrument, e.g. by reducing or eliminating the time needed to pump the analyser down to a suitable high vacuum after maintenance. Thus, embodiments require that the two points of a vacuum line are connected with variable axial distance in a hermetically sealed and flexible manner. To do this, a flexible tube connection, e.g. a vacuum hose, may be used. The vacuum hose may have sufficient length to allow the vacuum pump 50 to remain connected to the analyser 40 when the analyser has been slid out from the main housing to its maximum extent. When the analyser 40 is installed within the frame, the hose may be coiled up or otherwise stored away, e.g. within a housing of the vacuum pump. When the analyser 40 is being slid out from the main housing of the LC stack, the vacuum hose may be pulled into the main housing of the LC stack. Although this solution is relatively simple, one downside is that additional space and a guiding mechanism for the additional amount of tubing is needed.

[0041] Another solution is to provide a coaxial arrangement of two tubes with different diameters of which the bigger tube is sealed to the smaller tube. The seal may be formed from, for example, one or more O-rings, one or more shaft seals, a gland packing, a pneumatic or hydraulic rod seal, and the like. A downside of this solution is that all these types of seal are of a contact type, which can result in friction forces during axial movement. In addition, these types of seal can require rather accurate positioning of the two coaxial tubes relative to each other and are prone to frictional wear.

[0042] Another solution, as shown in Figures 2A-C, is in the form of a rolling bellows linear compensator. This solution solves the problems of high space requirements and avoids the need to use contact-type seals. In these embodiments, a coaxial arrangement of two rigid pipes 61, 62 of different diameters is used to save space while the contact type seal is replaced by a flexible membrane 63. This membrane may be made of a flexible material such as ethylene propylene diene monomer (EPDM) rubber, nitrile butadiene rubber (NBR), natural rubber (NR), or similar and may be reinforced by a fabric structure to carry the forces induced by fluid pressure. The membrane 63 may be connected to the outlet of the big pipe 61 and to the inlet of the small pipe 62.

[0043] To further describe the arrangement of components, and referring to Figures 2A and 2B, it is assumed that the vacuum line 60 is in its compressed or collapsed state, so that it has its shortest length. The direction of fluid flow is assumed to be from the left-hand side to the right-hand side or from the inlet of the big pipe 61 to the outlet of the small pipe 62.

[0044] As can be seen from Fig. 2B, in this compressed state, the flexible membrane 63 runs from the outlet of the bigger pipe 61, against the direction of flow, until about halfway the length of the bigger pipe 61 while being suspended against the inner wall of the bigger pipe 61 to a turning point, where it changes direction to the direction of flow while being supported against the outside wall of the inner tube 62. It then runs up to a point close to the outlet of the inner tube 62. When the system is in use, a vacuum is applied to the inlet of the bigger tube 61 and to the outlet of the smaller tube 62 and so a pressure difference will be applied to the membrane 63. The pressure will cause the membrane 63 to be pushed against the inner wall of the bigger, outer tube 61 and at the same time to be pushed against the outer wall of the inner tube 62. Thus, the tubing walls will support the membrane 63 and keep it from collapsing.

[0045] The only part of the membrane 63 that must support itself against the pressure difference between ambient and vacuum is the turning point where the membrane 63 changes from being supported by the outer tube 61 to being supported by the inner tube 62. This portion of the membrane 63 forms a curved single bellow that transitions from the inner wall of the outer tube 61 to the outer wall of the inner tube 62.

[0046] When the vacuum line 60 is moved, a relative motion between the outer and inner pipe will occur which will cause parts of the membrane 63 to be transferred from the outer to the inner tube (and vice versa), depending on the direction of the vacuum line movement. It is beneficial that there are no rigid parts that have a relative movement to each other while being in contact, which would cause frictional forces; such forces are in this case avoided by use of the membrane 63. The movement that happens between the membrane 63 and the tubing has a rolling manner; while the vacuum line 60 is expanding the membrane 63 rolls off the inner walls of the bigger tube 61 and rolls onto the outer wall of the inner tube 62 (and vice versa).

[0047] Figure 2C shows the vacuum line 60 arranged in its fully extended position.

[0048] It will be understood that embodiments provide reduced space requirements and substantially frictionless movement while being immune to misalignment.

[0049] Although various particular embodiments have been described above, various alternatives are possible.

[0050] For example, the vacuum line 60 may further comprise a guiding arrangement to restrain the relative movement of the first and second pipes to be in an axial direction. The vacuum line 60 may further comprise a locking mechanism to avoid unwanted movement of the vacuum line due to pressure forces.

[0051] Since the membrane 63 is connected to two pipes of different diameters at each end, it may have a certain shape to accept two diameters. For example, the membrane may be a custom made conically-shaped membrane. However, it would be desirable to use a standard hose-type membrane with a constant diameter. This hose may have an inner diameter fitting to the outer diameter of the smaller tube 62, in which case the hose should be stretched to fit onto the larger tube 61.

[0052] Alternatively, the hose may have an inner diameter fitting to the outer diameter of the big tube 61. In this case, since the chosen hose inner diameter is now equal to the outer diameter of the larger pipe 61 , it would not seem possible to connect it to the smaller tube 62.

[0053] To overcome this problem, a fitting may be introduced that is fixed to the outlet sided end of the inner tube 62. The fitting may comprise a ring 64 that is shaped like a gear with round teeth. The hose can then be mounted onto this ring 64 while being pressed onto it by another ring 65 that has a similar shape on its inside. This allows a wrinkled shape to be imposed onto the hose to reduce its circumscribed circle while maintaining the perimeter to be able to seal it to the inner tube.

[0054] Figure 3A shows the gear shaped inner ring 64 carrying the hose and the clamping ring 65 which has the inverted shape to clamp the hose from the outside onto the small pipe 62. Figure 3B shows a hose-type membrane 63 with imposed wrinkled to reduce its outer diameter while maintaining its perimeter.

[0055] Although particular embodiments relate to the integration of an analyser such as a mass spectrometer (MS) into a liquid chromatography system (LC), the analytical instrument could instead be a gas chromatography system (GC), an ion chromatography (IC) system, or similar stack of devices.

[0056] Although, as shown in Figure 1, the instrument may comprise several components arranged within the frame, in general the instrument can comprise two or more components arranged within the frame. That is, the instrument may comprise at least two boxes arranged in a stacked configuration.

[0057] The vacuum pump may be configured in any suitable manner. In some embodiments, a single vacuum pump is provided and used to pump the analyser. Alternatively, e.g. where high vacuum is required, the instrument may comprise a first vacuum pump such as a fore vacuum pump (i.e. a roughing pump), and a second vacuum pump such as a turbomolecular pump (and the instrument may optionally comprise one or more further vacuum pump(s)). In these embodiments, the one or more vacuum chambers may comprise a series of two or more vacuum chambers, including a fore vacuum chamber and one or more further vacuum chambers, with the turbomolecular pump being configured to pump the one or more further vacuum chambers and the fore vacuum pump being configured to pump the fore vacuum chamber and to act as a backing pump for the turbomolecular pump (i.e. to pump the output of the turbomolecular pump), e.g. as described in US Patent Application No. 2015 / 056060, the contents of which are incorporated herein by reference. In these embodiments, the series of vacuum chambers may be maintained at progressively lower pressures, with the mass analyser being arranged in the last vacuum chamber in the series (at the lowest pressure).

[0058] Although, as shown in Figure 1, the vacuum pump may be provided separately from (but connected to) the frame (“stack”), it would instead be possible for the vacuum pump to be provided within the frame (i.e. within the “stack”). Where there are two or more vacuum pumps, one or more or each of the vacuum pumps may be provided separately from (but connected to) the frame (“stack”) and / or one or more or each of the vacuum pumps may be provided within the frame (i.e. within the “stack”).

[0059] Figure 4 illustrates an embodiment in which the instrument is formed from two boxes 1, 2. A first box 1 contains a fore vacuum pump 51, and a second box 2 contains the analyser 40 and a turbomolecular pump 52. The turbomolecular pump 52 is provided adjacent to the analyser 40 within the same box 2, while the fore vacuum pump 51 is provided within a separate box 1 within the frame. The analyser box 2 may be mounted immediately above (on top of) the fore vacuum pump box 1. The fore vacuum pump 51 sustains the needed pumping speed required to keep the analyser 40 under vacuum. A flexible vacuum hose 60 connects the fore vacuum pump 51 to the fore vacuum chamber of the analyser 40 and / or to the turbomolecular pump 52.

[0060] In this embodiment, the turbomolecular pump 52 is, together with the analyser 40, slidably movable between the first position and the second position (and the fore vacuum pump 51 is not slidably movable). In other words, the analyser 40 can be horizontally moved / ejected out of its stack housing / box for service operations (such as repair, maintenance, etc.) while the turbomolecular pump 52 remains operational, ensuring uninterrupted vacuum inside the analyser 40. To maintain the turbomolecular pump 52, its connection with the fore vacuum pump 51 should be maintained when the analyser 40 is horizontally moved / ejected out of its stack housing / box. To do this, the vacuum line 60 may follow the analyser module 40 when it is ejected out of its stack housing / box.

[0061] Thus, the vacuum line 60 is configured to provide a vacuum connection between (i) the turbomolecular pump 52 and / or the fore vacuum chamber of the analyser 40, and (ii) the fore vacuum pump 51. The vacuum line 60 is configured such that this vacuum connection can be maintained when the analyser 40 and the turbomolecular pump 52 are in the first position, when the analyser 40 and the turbomolecular pump 52 are in the second position, and when the analyser 40 and the turbomolecular pump 52 are being moved between the first position and the second position.

[0062] This arrangement allows most service operations to be performed while the analyser 40 remains under vacuum. Service operations can included, for example, repair or replacement of electronic components (that are not needed to keep the instrument under vacuum). A typical mass spectrometer includes serval electronic devices that can be repaired or maintained in accordance with embodiments. These may include but are not limited to: internal computing systems for controlling the mass detector, digital control subsystems, data acquisition subsystems, ion optics driving electronics such as DC voltage or RF voltage supplies, electronics for driving the mass detecting subsystem such as a high voltage supply for driving an electrostatic ion trap, electronics to support ion generating such as electronics for providing the electrospray high voltage and for controlling the gases needed to support electrospray ionisation, one or more heaters such as a heater for baking out the vacuum manifold, a heater supporting heated electrospray ionization, or a heater heating the ion transfer tube, and so on.

[0063] Figure 5 shows detail of an embodiment comprising two boxes arranged in a stack configuration, with a box housing a mass spectrometer (MS) positioned above a box containing a fore vacuum pump. The instrument is operable in two different configurations while the vacuum of the analyser is not disturbed.

[0064] As shown in Figures 5A and 5C, in a first configuration the MS module is located inside its box. This configuration represents the standard working scenario, where the system can perform measurements.

[0065] As shown in Figures 5B and 5D, in a second configuration the MS module is ejected out of its box. This configuration is intended for service scenarios, allowing for maintenance or repair to be performed. During such service operations, the fore vacuum pump continues to pump out the fore vacuum chamber of the MS module, enabling the turbomolecular pump to function and to maintain vacuum within the MS system. Once the service intervention is completed, the MS module can be slid back inside its box. This allows the system to be returned quickly to its working configuration and for measurements to be resumed.

[0066] The MS module can be connected to its box using rails, e.g. horizontally mounted rails, enabling the functionality of ejection and sliding in.

[0067] In the embodiment depicted in Figure 5, the vacuum line is designed to be flexible, allowing it to follow the movement of the MS module while it is ejected or slid back into the box. Despite this movement, the vacuum line can sustain the vacuum connection between the MS system and the fore vacuum pump. In Figure 5D, the curved arrow indicates rotation of the flexible vacuum hose around a fixed pivot at the fore vacuum pump. When the MS system is moved out of the box, the connecting point of the flexible vacuum hose at the MS system side moves horizontally out while the length of the vacuum hose is unchanged. The vacuum line can be connected to the MS system either via the side or the back of its box, providing flexibility in the system design.

[0068] The fore vacuum pump itself does not need to move while the MS device is pulled out. The weight of the fore vacuum pump (with a typical weight of > 25 kg) can be used as a counterbalance to the change of the centre of gravity of the stack when the MS device is slid out. The fore vacuum pump can be oriented along or perpendicular to the direction of ejection or slide-in of the MS module.

[0069] The system is not limited to the two-box configuration of Figures 4 and 5 (nor to the four-box configuration of Figure 1). For example, the position of the mass spectrometer box is not limited to being directly above the fore vacuum pump box. Depending on the design needs, one or multiple other boxes can be positioned in between them.

[0070] In general, the stacked configuration of the instrument provides the flexibility to accommodate additional modules, thereby adding more functionality to the overall instrument. These modules can include any suitable components, such as another detection method, sample preparation capabilities, and so on. Furthermore, the instrument can support the integration of two different MS devices, each with distinct analytical properties such as different mass analysers or inlet systems. This versatility allows for customisation and adaptation of the instrument to specific analytical requirements.

[0071] Figure 6 shows an embodiment comprising a vertical stack of four boxes. The stack of boxes can include one or more LC detector(s), sampler(s) and / or binary pump(s). When the MS box is slidably moved out of the stack, the other boxes are kept in place. Therefore, the alignment of the other boxes as well as their connections (such as power, solvent tubing, etc.) do not need to be changed or moved when the MS box is slid out / in.

[0072] Although embodiments described above include a single analyser in the form of a mass analyser, it would be possible for the stack to include more than one analyser, e.g. to include another mass analyser and / or one or more analysers of a different type or types. For example, the stack may include any one or more of a UV detector, a fluorescence detector, a charged aerosol detector, etc. Although the present invention has been described with reference to various embodiments, it will be understood that various changes may be made without departing from the scope of the invention as set out in the accompanying claims.

Claims

CLAIMS1. An analytical instrument comprising: a frame; an analyser having one or more vacuum chambers, wherein the analyser is configured to be installed within a main body of the frame; and a vacuum line configured to provide a vacuum connection between the vacuum chamber(s) of the analyser and a vacuum pump; wherein the analyser and the frame are configured such that the analyser is slidably movable between a first position in which the analyser is installed within the main body of the frame and a second position in which the analyser is at least partially removed from the main body of the frame; and wherein the vacuum line is configured such that the vacuum connection between the vacuum chamber(s) of the analyser and the vacuum pump can be maintained when the analyser is in the first position, when the analyser is in the second position, and when the analyser is between the first position and the second position.

2. The instrument of claim 1 , wherein the vacuum line comprises: a telescopic arrangement comprising a first rigid pipe and a second rigid pipe; and / or a flexible tube.

3. The instrument of claim 2, wherein: an inner diameter of the first rigid pipe is greater than an outer diameter of the second rigid pipe; the second rigid pipe is arranged at least partially within the first rigid pipe in a substantially co-axial manner having a common axis; and the first and second rigid pipes are movable relative to one another along the common axis between a compressed state in which most or all of the second rigid pipe is arranged within the first rigid pipe, and an extended state in which most or all of the second rigid pipe is arranged outside of the first rigid pipe.

4. The instrument of claim 3, wherein the analytical instrument is configured such that the vacuum line is arranged in its compressed state when the analyser is in the first position, and such that the vacuum line is arranged in its extended state when the analyser is in the second position.

5. The instrument of any one of claims 2 to 4, comprising a seal between the first rigid pipe and the second rigid pipe.6 The instrument of any one of claims 2 to 5, wherein the vacuum line is configured such that the flexible tube runs from an outlet of the first rigid pipe against an inner wall of the first rigid pipe to a turning point and then runs against an outer wall of the second rigid pipe to or close to an outlet of the second rigid pipe.

7. The instrument of claim 6, wherein the vacuum line is configured such that only the turning point of the flexible tube is unsupported by the first and / or second rigid pipes.

8. The instrument of claim 7 when dependent on claim 3, wherein the vacuum line is configured such that, when the first and second rigid pipes are moved from the compressed state to the extended state and / or when the analyser is moved from the first position to the second position: a length of the part of the flexible tube that is supported by the inner wall of the first rigid pipe decreases; a length of the part of the flexible tube that is supported by the outer wall of the second rigid pipe increases; and a length of the unsupported turning point of the flexible tube remains substantially the same.

9. The instrument of any one of claims 2 to 8, wherein:the flexible tube has a constant inner diameter that corresponds to the outer diameter of the first rigid pipe; the flexible tube is connected to the outlet of the first rigid pipe and to a fitting arranged on or close to the outlet of the second rigid pipe; and the fitting has a radially undulating profile, such that its perimeter corresponds to the inner diameter of the flexible tube.

10. The instrument of claim 9, wherein the fitting is shaped like a gear with round teeth.

11. The instrument of any one of the preceding claims, further comprising: a vacuum pump connected to the vacuum line, wherein the vacuum pump is configured to maintain the vacuum chamber(s) of the analyser under vacuum; wherein the vacuum line is configured such that the vacuum pump can maintain the vacuum chamber(s) of the analyser under vacuum when the analyser is in the first position, when the analyser is in the second position, and when the analyser is between the first position and the second position.

12. The instrument of any one of the preceding claims, further comprising: a fore vacuum pump; and a turbomolecular pump; wherein the vacuum line is configured such that the fore vacuum pump and the turbomolecular pump can together maintain the vacuum chamber(s) of the analyser under vacuum when the analyser is in the first position, when the analyser is in the second position, and when the analyser is between the first position and the second position.

13. The instrument of claim 12, wherein: the turbomolecular pump is, together with the analyser, slidably movable between the first position and the second position; andthe vacuum line is configured to provide a vacuum connection between (i) the turbomolecular pump and / or the analyser, and (ii) the fore vacuum pump.

14. The instrument of any one of the preceding claims, wherein the instrument is a chromatography instrument, such as a liquid chromatography (LC) stack, a gas chromatography (GC) stack, or an ion chromatography (IC) stack.

15. The instrument of any one of the preceding claims, wherein the analyser is a mass spectrometer.

16. The instrument of claim 15, wherein the mass spectrometer comprises an electrostatic ion trap mass analyser.

17. The instrument of any one of the preceding claims, further comprising one or more further analyser(s).

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