Sprayer assembly

Abstract

A nebulizer assembly for an ion source is disclosed. The nebulizer includes a capillary tube having an outlet, a sheath for the capillary tube, and a resilient member. The sheath is movable relative to the capillary tube between a first position in which the sheath covers the outlet of the capillary tube and a second position in which the outlet of the capillary tube is exposed. The resilient member provides a restoring force to restore the position of the sheath to or toward the first position when the sheath is moved from the first position toward or toward the second position.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to U.S. Provisional Patent Application No. 62 / 965268, filed January 24, 2020; U.S. Provisional Patent Application No. 63 / 071081, filed August 27, 2020; and United Kingdom Patent Application No. 2014233.7, filed September 10, 2020. The entire contents of these applications are incorporated herein by reference. Technical Field

[0003] This invention generally relates to ion sources, and more particularly to ion source sprayer assemblies. Background Technology

[0004] Desorption electrospray ionization (“DESI”) is a form of ambient ionization in which a nebulizer device is used to direct a spray of solvent droplets onto the surface of the sample to be analyzed. The solvent droplets are used to desorb the analyte material from the sample surface. The analyte material released (desorbed) from the sample can then be collected and analyzed by analytical instruments such as mass and / or ion mobility spectrometers.

[0005] Figure 1 A typical DESI sprayer 10 is shown. (As shown...) Figure 1 As shown, the atomizer 10 includes a solvent capillary 12 and a gas capillary 13. The solvent capillary 12 is coaxially arranged within the gas capillary 13, with the solvent outlet 12A of the solvent capillary 12 extending beyond the distal end of the gas capillary 13. The solvent flow 14 supplied to the solvent capillary 12 is charged by means of a high-voltage source 18 and guided toward the sample 1 with the assistance of the atomizing gas flow 15 supplied to the gas capillary 13.

[0006] The resulting (primary) charged droplet 11 spray is able to desorb the analyte material from the surface of sample 1, and the (secondary) droplets carrying the desorbed ionized analyte can then travel via transfer capillary 20 to the atmospheric pressure interface 22 of an analytical instrument (not shown), such as a mass and / or ion mobility spectrometer.

[0007] The applicant has recognized that the solvent capillary 12 may be relatively fragile and therefore easily damaged. The applicant has proposed an improved arrangement in WO 2018 / 189534, the entire contents of which are incorporated herein by reference, in which the solvent outlet 12A of the solvent capillary 12 is arranged behind a nozzle or shroud.

[0008] However, the inventors believe that there is still room for improvement for the ion source and for the ion source sprayer assembly. Summary of the Invention

[0009] According to a first aspect, there is provided a sprayer assembly, the sprayer assembly comprising:

[0010] a capillary tube having an outlet;

[0011] a sheath for the capillary tube; and

[0012] a resilient member;

[0013] wherein the assembly is configured such that the sheath is movable relative to the capillary tube between a first position in which the sheath covers the outlet of the capillary tube and a second position in which the outlet of the capillary tube is not covered by the sheath; and

[0014] wherein the assembly is configured such that the resilient member provides a restoring force to restore the position of the sheath to or towards the first position when the sheath is moved from the first position to or towards the second position.

[0015] Various embodiments relate to a sprayer assembly for an ion source, such as a desorption electrospray ionisation ("DESI") sprayer assembly. The assembly comprises a (solvent) capillary tube and a sheath (fitted cap) for the capillary tube, which can act as a protective cap for the (relatively more fragile) capillary tube. The sheath is movable relative to the capillary tube between a first position in which the sheath covers and thus protects the (solvent ejection) outlet or tip of the capillary tube and a second position in which the sheath does not cover the outlet (tip), e.g. in which the outlet is exposed (for normal use). The assembly further comprises a resilient member, such as a compression spring, which acts to bias the sheath towards the first position in which the outlet is covered (protected) by the sheath (in which the outlet is not exposed).

[0016] The inventors have recognised that, whilst arranging a solvent capillary tube behind a nozzle, e.g. as described in WO 2018 / 189534, can provide protection for the capillary tube in normal use, it can be desirable to remove the nozzle, e.g. in order to clean the nozzle, or in order to replace the nozzle with a different nozzle, which can have a different size and / or configuration. This can leave the capillary tube, in particular the solvent ejection tip of the capillary tube, exposed and vulnerable to damage. Furthermore, the capillary tube can typically be a "consumable" item which is replaced relatively frequently, so it is desirable to ship and install independently of the protective element, such as the nozzle. Thus, the capillary tube can be vulnerable to damage during shipping and installation. Furthermore, the solvent ejection tip of the capillary tube can be relatively sharp, so is associated with a risk of injury.

[0017] By providing a sheath for the capillary, the capillary can be protected, e.g. during transport and installation. Moreover, the risk of injury can be reduced. Moreover, by biasing the position of the sheath relative to the capillary with the resilient member, the sheath can retract to expose the outlet to allow normal use, but then automatically extend to cover and thus protect the outlet, e.g. when the nozzle is removed.

[0018] Thus, it will be appreciated that various embodiments provide an improved sprayer assembly for an ion source.

[0019] The assembly can be configured such that the resilient member elastically deforms when the sheath is moved from the first position towards or toward the second position.

[0020] The resilient member can be a spring, such as a compression spring. The assembly can be configured such that the compression spring is compressed when the sheath is moved from the first position towards or toward the second position.

[0021] The compression spring can surround the capillary. The assembly can be configured such that the compression spring can be compressed between a collar provided on the capillary and a shoulder (within the sheath).

[0022] The sheath can comprise a cavity, and the resilient member (compression spring) can be provided in the cavity within the sheath. This can hold and protect the resilient member, and can allow the capillary, sheath and resilient member to be provided together in the form of a cartridge.

[0023] The sheath can be formed of any suitable material, such as metal and / or ceramic and / or plastic, e.g. PEEK (polyether ether ketone) or PPS (polyphenylene sulfide).

[0024] The sheath can be insulated. For example, the sheath can be formed of an insulating material, such as a plastic, e.g. PEEK (polyether ether ketone) or PPS (polyphenylene sulfide). Additionally or alternatively, the sheath can have an insulating coating, e.g. a plastic coating. For example, the sheath can be formed of a metal with an insulating coating.

[0025] The sheath can comprise one or more gas outlets configured to emit a gas, e.g. such that the gas interacts with (atomised) solvent emitted from the outlet of the capillary to produce a spray of solvent droplets.

[0026] The sheath can include one or more gas conduits. The one or more gas conduits can be configured to connect one or more gas inlets of the sheath to one or more gas outlets. Nebulizing gas can thus flow from the one or more gas inlets through the one or more gas conduits to the one or more gas outlets.

[0027] The gas conduits can be internal to the sheath, or formed in an exterior of the sheath.

[0028] The sheath can include an axial bore configured to hold the capillary tube, and the one or more gas conduits can each be arranged parallel to the axial bore.

[0029] The sheath can be formed as a single (integrated) part, or can be formed from multiple parts. For example, the sheath can be formed from a main sheath body and an insert arranged within the main sheath body. The cavity can be formed in the main sheath body. The axial bore and the one or more gas conduits can be formed in the sheath insert.

[0030] The capillary tube can be formed from a metal, such as stainless steel.

[0031] The outlet of the capillary tube can be tapered. The outlet of the capillary tube can be configured to emit solvent (droplets).

[0032] The assembly can include a sprayer assembly body. The capillary tube, the sheath, and the resilient member can be removably attached to the body.

[0033] The capillary tube, the sheath, and the resilient member can be configured as a cartridge, and the cartridge can be removably attached to the body. The body can include an aperture configured to receive the cartridge.

[0034] The assembly can further include a removable nozzle. The nozzle can be removably attached to the body.

[0035] The nozzle can include an aperture. Solvent (droplets) emitted by the capillary tube can be arranged to pass through the aperture of the nozzle.

[0036] The assembly can be configured such that installation of the nozzle moves the sheath to the second position, and removal of the nozzle moves the sheath to the first position.

[0037] The assembly can be configured such that when the nozzle is attached to the body, the cartridge (sheath) is held within the body.

[0038] According to another aspect, there is provided a sprayer assembly, the sprayer assembly comprising:

[0039] a sprayer assembly body;

[0040] a capillary tube having an outlet;

[0041] a sheath for the capillary tube; and

[0042] a nozzle removably attachable to the body;

[0043] wherein the assembly is configured such that the sheath is movable relative to the capillary tube between a first position in which the sheath covers the outlet of the capillary tube and a second position in which the outlet of the capillary tube is not covered by the sheath (in which the sheath does not cover the outlet of the capillary tube); and

[0044] wherein the assembly is configured such that attachment of the nozzle to the body moves the sheath to the second position and removal of the nozzle from the body moves the sheath to the first position.

[0045] The assembly according to this aspect can have any one or more or each of the optional features described herein in relation to other aspects, as appropriate.

[0046] The assembly according to this aspect can comprise a resilient member and can be configured such that, when the sheath is moved from the first position towards or towards the second position, the resilient member provides a restoring force which acts to restore the position of the sheath to or towards the first position.

[0047] In various aspects and embodiments, the assembly can be configured such that, when the nozzle is attached to the body, the nozzle pushes the sheath to the second position.

[0048] The assembly can be configured such that, when the nozzle is connected to the body, the sheath is held in the second position.

[0049] The assembly can be configured such that, when the nozzle is removed from the body, the restoring force moves the sheath towards or towards the first position.

[0050] The sheath can be configured to guide the nozzle into coaxial alignment with the capillary tube when the nozzle is attached to the body.

[0051] According to another aspect, there is provided a sprayer assembly, the sprayer assembly comprising:

[0052] a sprayer assembly body;

[0053] a capillary tube;

[0054] a guide configured to hold the capillary tube; and

[0055] a nozzle removably attached to the guide;

[0056] wherein the guide is configured to guide the nozzle into coaxial alignment with the capillary tube when the nozzle is attached to the guide.

[0057] The assembly according to this aspect can have any one or more or each of the optional features described herein in relation to other aspects, as appropriate.

[0058] The inventors have recognised that the spray produced by a sprayer having a nozzle can be particularly sensitive to the alignment (centring) between the capillary tube and the nozzle, and that spray reproducibility can therefore be improved by providing a nozzle guide.

[0059] The alignment (centring) can be such that the (aperture of the) nozzle is (coaxially) aligned (positioned in line with) the (outlet of the) capillary tube.

[0060] The nozzle can comprise an aperture configured to fit coaxially over the nozzle guide (sheath).

[0061] The capillary tube can be arranged coaxially with the nozzle guide (sheath), for example held in a central axial aperture of the nozzle guide (sheath), and the nozzle aperture can be arranged coaxially with the nozzle aperture, for example on a central axis of the nozzle.

[0062] An outlet end of the nozzle guide (sheath) can have a conical or frustoconical shape, and an inner surface of the nozzle aperture can have a complementary conical or frustoconical shape.

[0063] The nozzle can be removably attached to the guide by a threaded or bayonet fitting.

[0064] The inventors have recognised that the spray produced by a sprayer having a nozzle can be particularly sensitive to the distance between the aperture of the nozzle and the outlet of the capillary tube. It has further been recognised that the use of a bayonet fitting can reduce variability in this distance, and that spray reproducibility can therefore be improved by using a bayonet fitting.

[0065] The bayonet fitting can comprise a connector body and one or more lugs. The body can comprise one or more recesses arranged to accommodate the one or more lugs.

[0066] The sprayer assembly can be configured such that the distance between the nozzle orifice and the capillary outlet is adjustable, e.g. controllably adjustable. Some or all of the rear surface of the connector body can be bevelled, inclined and / or curved.

[0067] The assembly can comprise a nozzle assembly comprising the nozzle and the threaded or bayonet fitting, wherein the nozzle is removable from the threaded or bayonet fitting.

[0068] The nozzle can be tethered to the threaded or bayonet fitting.

[0069] According to another aspect, there is provided a sprayer assembly, the sprayer assembly comprising:

[0070] a sprayer assembly body;

[0071] a cartridge housing a capillary; and

[0072] a nozzle removably attached to the body;

[0073] wherein the assembly is configured such that, when the nozzle is attached to the body, the cartridge can be held within the body (by the nozzle).

[0074] The assembly according to this aspect can have one or each of the optional features described herein in relation to the other aspects, as appropriate.

[0075] By providing a removable cartridge housing a capillary, installation of the capillary can be made more straightforward and more user-friendly, and the risk of capillary damage during installation of the capillary can be reduced.

[0076] The body can comprise one or more supply ports. The assembly can be configured such that, when the cartridge is held within the body, the one or more supply ports are coupled to one or more corresponding ports of the cartridge.

[0077] The body can comprise a solvent supply port. The body can comprise a gas supply port. The body can comprise a high voltage supply port.

[0078] The assembly can be configured such that, when the cartridge is held within and / or connected to the body, the solvent supply port is coupled to the capillary.

[0079] The assembly can be configured such that, when the cartridge is held within and / or connected to the body, the gas supply port is coupled to the cartridge.

[0080] The assembly can be configured such that the high voltage supply port is coupled to the cartridge when the cartridge is held within and / or connected to the body.

[0081] The nebuliser assembly can be configured to generate a spray of solvent droplets. The spray of solvent droplets can be suitable for desorbing analyte material from a surface of a sample.

[0082] According to one aspect, there is provided an ion source comprising a nebuliser assembly as described above.

[0083] The ion source can further comprise a sampling inlet configured to collect analyte. The analyte can be generated as a result of a spray generated by the nebuliser assembly interacting with a sample.

[0084] The sampling inlet can be connected to an analytical instrument, such as a mass and / or ion mobility spectrometer.

[0085] According to another aspect, there is provided a method of generating a spray of droplets, the method comprising using a nebuliser assembly as described above to generate a spray of droplets.

[0086] According to another aspect, there is provided a method of ionising a sample, the method comprising:

[0087] providing a nebuliser assembly as described above; and

[0088] directing a spray generated by the nebuliser assembly towards a sample.

[0089] According to another aspect, there is provided a method of analysing a sample, the method comprising:

[0090] providing a nebuliser assembly as described above;

[0091] directing a spray generated by the nebuliser assembly towards a sample to generate analyte; and

[0092] analysing the analyte.

[0093] The analyte can comprise analyte ions. Additionally or alternatively, the analyte can be ionised to generate analyte ions.

[0094] Analysing the analyte can comprise analysing analyte ions to determine their mass-to-charge ratio and / or ion mobility, and / or determining the mass-to-charge ratio and / or ion mobility of ions derived from the analyte ions (e.g. by fragmenting the analyte ions). BRIEF DESCRIPTION OF DRAWINGS

[0095] Various implementations will now be described, by way of example only, and with reference to the attached figures, wherein:

[0096] Figure 1 A desorption electrospray ionization ("DESI") ion source is shown;

[0097] Figure 2 A desorption electrospray ionization ("DESI") sprayer with a nozzle is shown;

[0098] Figure 3A is an exploded view of a sprayer cartridge assembly according to various embodiments, Figure 3B is a cross-sectional view of a sprayer cartridge assembly according to various embodiments, Figure 3C is a cross-sectional view of a sprayer cartridge assembly according to various embodiments, Figure 3D is a perspective view of a sprayer cartridge assembly according to various embodiments, and Figure 3E is an internal view of a sprayer cartridge assembly according to various embodiments;

[0099] Figure 4A A sprayer assembly including the sprayer cartridge assembly of Figure 3 mounted for use according to various embodiments is shown, Figure 4B is an exploded view of a sprayer assembly, Figure 4C is an exploded view of a sprayer assembly, Figure 4D is a cross-section of a sprayer nozzle according to various embodiments, and Figure 4E is a sprayer nozzle according to various embodiments;

[0100] Figure 5A is a cross-section of a sprayer assembly according to various embodiments, and Figure 5B is a cross-section of a sprayer assembly according to various embodiments;

[0101] Figure 6A is a sprayer assembly according to various embodiments, Figure 6B is a sprayer assembly according to various embodiments, Figure 6C is a cross-section of a sprayer assembly according to various embodiments, Figure 6D is a cross-section of a sprayer assembly according to various embodiments, and Figure 6E is a cross-section of a sprayer assembly according to various embodiments;

[0102] Figure 7A is a cross-section of a sprayer assembly according to various embodiments, and Figure 7B is a cross-section of a sprayer assembly according to various embodiments;

[0103] Figure 8 is a side view of a manifold body of a sprayer assembly according to various embodiments;

[0104] Figure 9AA perspective rear view of a sprayer nozzle according to various embodiments is shown, and Figure 9B A perspective view of the manifold body of a sprayer assembly according to various embodiments is shown;

[0105] Figure 10 Cross-sections of sprayer assemblies according to various embodiments are shown; and

[0106] Figure 11A An end view of the sheath of a sprayer assembly according to various embodiments is shown, and Figure 11B A cross-section of the sheath of a sprayer assembly according to various embodiments is shown. Detailed Implementation

[0107] Figure 1 A typical desorption electrospray ionization (“DESI”) ion source, including a sprayer 10, is shown. Figure 1 As shown, the atomizer 10 includes a solvent capillary 12 and a gas capillary 13. The solvent capillary 12 (dispenser) is coaxially arranged within the gas capillary 13, with the solvent outlet or tip 12A of the solvent capillary 12 extending beyond the distal end of the gas capillary 13. The solvent flow 14 supplied to the solvent capillary 12 is charged by means of a high-voltage source 18 and guided toward the sample 1 with the assistance of the atomizing gas flow 15 supplied to the gas capillary 13.

[0108] The resulting spray of (primary) charged droplets 11 is capable of desorbing analyte material from the surface of sample 1, and the (secondary) droplets carrying the desorbed ionized analyte can then travel via transfer capillary 20 to the atmospheric pressure interface 22 of an analytical instrument (not shown), such as a mass and / or ion mobility spectrometer. The ions can then be analyzed to determine their mass-to-charge ratio and / or ion mobility, and / or the mass-to-charge ratio and / or ion mobility of ions originating from the initial ions (e.g., by cleaving the initial ions).

[0109] The applicant has recognized that the solvent capillary 12 may be relatively fragile (e.g., containing fused silica) and therefore easily damaged.

[0110] Figure 2 An alternative desorption electrospray ionization (“DESI”) atomizer arrangement is shown, wherein the outlet (tip) 12A of the solvent capillary 12 is located behind the nozzle (nose cone or shield) 16, and the solvent capillary 12 is positioned in line with the orifice 17 provided in the nozzle 16, such that the solvent spray 11 is guided from the solvent capillary 12 through the orifice 17 onto the sample surface.

[0111] As discussed in WO 2018 / 189534, the nozzle 16 can serve to protect the solvent capillary 12 in use. The aperture 17 can also provide some focusing of the solvent spray 11.

[0112] As discussed above, the inventors have recognised that, while the nozzle 16 is able to provide protection to the solvent capillary 12 in normal use, it can be desirable to remove the nozzle 16, for example in order to service / clean or replace the nozzle with a different size, leaving the solvent capillary 12 vulnerable to damage. Furthermore, the solvent capillary can be vulnerable to damage during transportation and installation.

[0113] The inventors have further recognised that, in arrangements with a nozzle 16, it is necessary to very accurately align the outlet 12A of the solvent capillary 12 with the aperture 17 of the nozzle 16 in order to achieve consistent performance.

[0114] In various embodiments, there is provided a sprayer assembly comprising a "sleeve" or sheath (i.e. a tight-fitting cap) for a (solvent) capillary. The sheath (sleeve) is movable relative to the capillary between a first, protected position in which the sheath covers the (solvent-dispensing) outlet (tip) of the capillary, and a second, exposed position in which the outlet (tip) is exposed (i.e. not covered by the sheath) for normal use. An elastic member, such as a compression spring, provides a restoring force which serves to restore the position of the sheath to the protected position when the sheath is moved away from the protected position towards or towards the exposed position.

[0115] In various embodiments, as will be discussed further below, installation of a nozzle causes the sheath to move to the second, exposed position, whereas when the nozzle is removed the restoring force provided by the elastic member (compression spring) causes the sheath to return to the first, protected position.

[0116] Thus, in various embodiments, there is provided a spring-loaded sheath which is able to protect a solvent capillary, for example when a nozzle is removed.

[0117] In various embodiments, as will be discussed further below, the sheath is additionally configured such that, when a nozzle is installed, the outlet of the solvent capillary is aligned with the aperture of the nozzle.

[0118] Figure 3A - Figure 1 illustrates a desorption electrospray ionisation ("DESI") sprayer assembly according to various embodiments. The assembly of Figure 1 is in the form of a cartridge 10 comprising a solvent capillary 12 and an elastic member in the form of a compression spring 13, which is surrounded by a sheath 14.

[0119] Figure 3A is an exploded view of the assembly, Figure 3Ba sheath 31 is shown positioned relative to the capillary 32 such that the outlet (solvent discharge tip) 32A of the capillary is exposed for normal use, Figure 3C a sheath 31 is shown in a protected position in which the outlet (tip) 32A is covered by the sheath 31 and is thus protected from damage, Figure 3D is a perspective view of the assembly in the exposed position, and Figure 3E shows an internal view of the sheath 31.

[0120] The capillary 32 can be supplied with solvent and discharge solvent and can therefore be referred to as a solvent or spray capillary or discharge. The capillary 32 can be generally tubular, with solvent being supplied at one axial (solvent receiving) (inlet) end and being discharged at the opposite axial end, i.e. at the outlet (or solvent discharge tip) 32A. The outlet (solvent discharge tip) 32A of the capillary can be tapered.

[0121] The capillary 32 can be formed of any suitable material, such as fused silica. In embodiments, the capillary 32 is formed of an electrically conductive (metallic) material, such as stainless steel. The inventors have found that an electrically conductive capillary is able to reduce or avoid the build-up of electrical charge, which can otherwise create an undesirable electric field. Furthermore, although a metallic (e.g. stainless steel) solvent capillary 32 can not be as fragile as, for example, fused silica, it can still benefit from a protective sheath, for example due to the risk of bending.

[0122] Liquid solvent can be provided to the capillary 32 at a solvent flow rate of, for example, between about 0.05 and 10 pL / min. In embodiments, the solvent flow rate can be between about 1 and 4 pL / min, such as between about 2 and 3 pL / min, or about 2 pL / min.

[0123] The solvent can comprise any suitable and desired solvent. For example, the solvent can comprise an organic solvent, such as acetonitrile. As another example, the solvent can comprise methanol. Other suitable solvents can include dichloromethane (optionally mixed with methanol), dichloroethane, tetrahydrofuran, ethanol, propanol, nitromethane, toluene (optionally mixed with methanol or acetonitrile), or water. The solvent can also comprise an acid, such as formic acid or acetic acid. The solvent can also comprise one or more additives.

[0124] The solvent droplets can be electrically charged. Accordingly, a voltage can be applied to the nebulizer assembly in order to charge the solvent and / or solvent droplets. For example, a voltage of between about 0 and 5 kV can be applied to the capillary 32 or solvent in order to charge the solvent droplets. In embodiments, a voltage of between about 2 and 3 kV, such as a voltage of about 2.5 kV, can be applied to the capillary 32 or solvent. In embodiments, a voltage of between about 1 and 5 kV, such as between about 1 and 3 kV, such as a voltage of about 1 kV, can be applied to the capillary 32 or solvent.

[0125] In embodiments, a voltage of between about 1 and 5 kV is applied to the capillary 32 or solvent, wherein the liquid solvent is provided to the capillary 32 at a flow rate of between about 2 and 3 pL / min.

[0126] The sheath 31 can be generally configured as a tight fitting (protective) cover for the capillary 32. The sheath 31 can be configured to (at least partially) coaxially surround the capillary 32. The sheath 31 can be configured such that the sheath 31 is slidable over the capillary 32 to move relative to the capillary 32 between a (first) protective position and a (second) exposed position.

[0127] In embodiments, the (axial) length of the sheath 31 is such that the sheath is able to cover a substantial (majority) of the capillary 32, such as at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80% or at least 90% of the (axial) length of the capillary. The inventors have found that a longer sheath length can improve capillary alignment.

[0128] As can be seen in Figure 3B and Figure 3C the (axial) length of the sheath 31 can be such that the solvent receiving end (inlet) of the capillary 32 is exposed (not covered by the sheath 31) when the sheath is in the (first) protective position and when the sheath is in the (second) exposed position in order to allow for convenient coupling to a solvent supply.

[0129] The sheath 31 can be formed from any suitable material. The sheath 31 can be formed from a material that is relatively less brittle, i.e. less prone to breaking or bending, than the capillary, such that the sheath is able to protect the capillary from damage. In embodiments, the sheath is formed from a metal and / or a ceramic and / or a plastic, such as PEEK (polyether ether ketone) or PPS (polyphenylene sulfide).

[0130] The sheath 31 can be electrically insulating. For example, the sheath 31 can be formed from an electrically insulating material and / or comprise an electrically insulating coating. Forming an electrically insulating sheath 31 means that the sheath is able to (also) act as an insulator for the electrically conductive (metal) capillary.

[0131] As can be seen inFigure 3A As seen in -E, the sheath 31 can be generally cylindrical, and can be hollow, that is, can have a generally tubular shape.

[0132] The sheath 31 can have an axial bore that can be configured and dimensioned to accommodate the capillary tube 32 therein. The capillary tube-receiving axial bore of the sheath 31 can be generally cylindrical, and can run centrally along the (entire) axial length of the sheath 31. Having the capillary tube-receiving axial bore of the sheath 31 centrally disposed within the sheath can facilitate alignment of the capillary tube 32 relative to other components of the assembly, e.g., relative to a nozzle (not shown in FIG. 3).

[0133] As can be seen in Figure 3A As seen in -E, at least a portion 31A of the axial bore can be configured and dimensioned to retain the capillary tube 32 such that, when installed within the axial bore, the capillary tube 32 is retained (clamped) by the sheath 31 (and properly aligned with other components of the assembly). Thus, some or all of the length of the axial bore can have a first diameter that can be slightly greater than the diameter of the capillary tube 32 (e.g., with a tight clearance, such as approximately 0.1 mm), such that, when installed within the axial bore, the capillary tube 32 is clamped by the sheath 31 (and properly aligned with other components of the assembly).

[0134] It would be possible for the axial bore to have the same diameter along the entire length of the sheath 31, in which case the axial bore can have the first diameter along its entire length. However, in various embodiments, the axial bore has a plurality of different diameters along the length of the sheath 31. In this case, the axial bore can have at least one axial segment 31A having the first diameter (such that the capillary tube 32 is clamped by the sheath 31), but can have one or more other segments 31B having a diameter that is greater than the first diameter.

[0135] For example, in various embodiments, the axial bore includes a first axial segment 31A having a first diameter (and can be located at an end of the sheath proximate the capillary tube outlet 32A), and a second axial segment or cavity 31B having a second diameter that is greater than the first diameter (and can be located at the other end of the sheath).

[0136] As can be seen in Figure 3A As seen in -C, in embodiments, the restoring force can be provided by a compression spring 33. However, it is contemplated that other resilient members can be used to provide the restoring force. The resilient member (compression spring 33) can thus be used to bias the position of the sheath 31 relative to the capillary tube 32 toward a protected position in which the solvent ejection tip (outlet) 32A of the capillary tube 32 is protected by the sheath 31.

[0137] The assembly can be configured such that the resilient member (compression spring 33) provides a restoring force between the capillary 32 and the sheath 31 in any suitable manner. In embodiments, the resilient member is arranged and configured such that it elastically deforms, e.g. compresses, when the sheath 31 is moved from the first exposed position or towards the second protective position relative to the capillary 32, such that it provides a restoring force.

[0138] For example, as can be seen in Figure 3A The compression spring 33 can surround the capillary 32, e.g. as can be seen in Figure 3B The compression spring 33 can be under compression between the collar 32B provided on the capillary 32 and the shoulder 31C in the sheath 31 in the exposed position, as shown in Figure 3C The compression spring 33 can be unloaded in the protective position, as can be seen in

[0139] In embodiments, the second axial section or cavity 31B of the sheath 31 can be configured to house the resilient member (compression spring 33). The end cap 34 can be configured to close the cavity 31B so as to retain the resilient member 33 (and the capillary 32) within the sheath 31. Providing the resilient member within the cavity 31B of the sheath can protect the resilient member from damage. Furthermore, this arrangement can enable the sheath 31, the capillary 32 and the resilient member 33 to be conveniently provided together as a cartridge assembly 30.

[0140] The assembly can be supplied with a flow of atomising gas. The assembly can be configured such that the flow of atomising gas interacts with the (atomised) solvent emitted at the outlet (solvent emission tip) 32A of the capillary 32 to produce a spray of solvent droplets. The atomising gas can suitably be provided at a pressure of between about 0.1 and 10 bar, e.g. between about 0.2 and 5 bar, e.g. between about 3 and 5 bar, e.g. about 4 bar or between about 0.5 and 2 bar. The atomising gas can be any suitable gas, such as nitrogen.

[0141] The assembly can further comprise a gas capillary which can surround the solvent capillary 32, wherein the atomising gas is supplied to the gas capillary. However, in embodiments, the sheath 31 acts as an atomising gas conduit for the assembly.

[0142] Thus, as can be seen in Figure 3DAs best seen in FIG. 1 1, in embodiments, the sheath can include one or more gas inlets 36A configured to receive a flow of (atomizing) gas. The one or more gas inlets 36A can include one or more gas-receiving apertures disposed in a sidewall of the sheath 31, and can be arranged and configured such that gas can enter the second axial segment or cavity 31 B within the sheath via the one or more gas inlets 36A. The sheath can also include one or more gas outlets 36B (e.g., one or more gas-discharge apertures) configured to discharge the received gas such that the gas interacts with the (atomizing) solvent discharged at the outlet (solvent-discharge tip) 32A of the capillary 32 to produce a spray of solvent droplets.

[0143] As can be best seen in FIG. 1 1, Figure 3E As best seen in FIG. 1 1, in embodiments, the sheath 31 can include one or more gas conduits 36C connecting the one or more gas inlets 36A to the one or more gas outlets 36B (via the second axial segment or cavity 31 B). Integrating the sheath and gas conduit functions in this way provides a simpler assembly.

[0144] The one or more gas conduits 36C can be configured as desired. As can be seen in FIG. 1 1, Figure 3E As can be seen in FIG. 1 1, in embodiments, each gas conduit 36C can run along at least a portion of the axial length of the sheath 31, e.g., along the length of (the first axial segment 31 A of) the capillary-receiving axial aperture and parallel thereto. The gas conduit(s) can be of any shape, such as generally cylindrical.

[0145] In embodiments, as can be seen in FIG. 1 1, Figure 3E As can be seen in FIG. 1 1, in embodiments, the one or more axial gas conduits 36C can each be radially displaced from the central axis of the sheath 31 by the same or a similar radial distance, such that the central aperture and the gas conduits 36C (of the first axial segment 31 A) can together form a single connected cavity within the sheath 31.

[0146] In embodiments, there are multiple gas conduits 36C equally spaced apart. The central aperture (of the first axial segment 31 A) can thus be defined by a radially inward projection of the sheath between the multiple gas conduits 36C, which can be configured to hold the capillary 32 centrally within the sheath 31.

[0147] While in FIG. 1 1, Figure 3EIn one embodiment, the central orifice and the gas conduit 36C together form a single connected cavity within the sheath 31. However, in another embodiment, one or more of the central orifice and the gas conduit 36C may be separate (each may include a separate orifice (cavity) within the sheath 31). In these embodiments, one or more of the central orifice and the gas conduit 36C may be separated by the (inner) wall of the sheath 31.

[0148] Although Figure 3E The embodiment has three gas conduits 36C, but it is contemplated that fewer or more gas conduits may be provided. For example, the sheath 31 may include one, two, three, four, five, six, seven, eight or more gas conduits 36C.

[0149] Although Figure 3E In one embodiment, the gas conduit 36C is inside the sheath 31, but it is contemplated that the gas conduit could be configured as a channel in the outer surface of the sheath. In this case, a gas flow path can be defined between the outer surface of the sheath and the body or manifold in which the sheath is mounted.

[0150] In various embodiments, the assembly is configured as a replaceable (removable) cartridge. For example, as shown in FIG3, the assembly may be a replaceable cartridge assembly 30 including a solvent capillary 32, a sheath 31, and an elastic member 33. In these embodiments, installing the solvent capillary into the analytical instrument may include installing the cartridge assembly 30 as a single unit into the analytical instrument. This means that the solvent capillary can be protected by the sheath during installation.

[0151] Figure 4A A cartridge assembly 30, according to various embodiments, is shown mounted into the body or manifold 41 of an analytical instrument for use. The manifold (body) 41 can be formed of suitable materials such as metal and / or ceramic and / or plastics such as PEEK (polyetheretherketone) or PPS (polyphenylene sulfide). In these embodiments, the cartridge 30 can be configured as an orifice that slides into the body 41 and can be held there by attaching a nozzle 46 to the body 41. Figure 4A As seen in the image, in the installation position, the sheath 31 can be positioned in the exposed position, such that the outlet (solvent discharge tip) 32A of the capillary 32 is not covered by the sheath 31. Therefore, in the installation position, the compression spring 33 is under compression.

[0152] If able to Figure 3A -D and Figure 4A As seen in the image, the cylinder assembly 30 may also include one or more O-ring seals 35 to provide a seal when the cylinder assembly 30 is installed in the manifold body 41.

[0153] The body 41 can be configured such that when the cartridge assembly is installed in the aperture, the cartridge assembly 30 is coupled to the gas input fitting 42 and the solvent input fitting 43. The manifold body 41 can be further configured such that when the cartridge assembly is installed in the aperture, the high voltage source is coupled to the solvent stream, e.g., via the high voltage port 44.

[0154] Thus, when the cartridge assembly 30, gas fitting 42, and solvent inlet fitting 43 are installed in the manifold body 41, a gas stream can be received by one or more gas inlets 36A of the sheath 31 and a solvent stream can be received by the inlet (solvent receiving end) of the solvent capillary 32. Further, a high voltage can be received from the high voltage port 44 for application to the solvent.

[0155] Figure 4B and Figure 4C An exploded view of the assembly including the cartridge assembly 30 and the manifold body 41 is shown. As can be seen in these figures, the assembly can include one or more fasteners for attaching the manifold body 41 to (the rest of) the analytical instrument, e.g., in the form of one or more threads 411 that can be tightened to the manifold body 41.

[0156] In embodiments, as can be seen in Figure 4A The capillary outlet 32A is positioned behind the removable nozzle 46, as can be seen in FIG. C. The removable nozzle 46 can have an aperture, wherein the capillary 32 can be arranged to direct a spray of solvent droplets through the aperture.

[0157] The nozzle 46 can take any suitable form as desired. In embodiments, the nozzle can have a generally conical or frusto-conical shape. The shape of the aperture of the nozzle can be generally circular and can be positioned centrally, that is, on the central axis of the nozzle.

[0158] The size of the aperture disposed within the nozzle 46 can be selected as desired, e.g., depending on the desired spot size and the diameter of the capillary 32. Smaller spot sizes can be used to produce higher (spatial) resolution data, but provide lower sensitivity. Larger spot sizes can be used to achieve greater sensitivity, but have lower (spatial) resolution.

[0159] In embodiments, the diameter of the aperture can range from about 10 microns to about 250 microns. For example, the diameter of the aperture can range from about: (i) 50 microns to about 250 microns; (ii) 100 microns to about 250 microns; (iii) 150 microns to about 250 microns; or (iv) 175 microns to about 250 microns. While smaller apertures generally produce a spray having an initial smaller diameter, the spray produced from smaller apertures also suffers from greater divergence. The inventors have found that a nozzle diameter of about 200 microns can produce a particularly reproducible spray.

[0160] The nozzle 46 can be maintained at earth potential. Thus, the assembly can further comprise means for grounding the nozzle 46, for example in the form of a grounding clip 412. However, it is also envisaged that the nozzle 46 can be charged. For example, the nozzle 46 can be supplied with a voltage to charge (or further charge) the solvent spray as it passes through the nozzle 46 (for example, as an alternative or in addition to applying a voltage to the capillary 32). The voltage applied to the nozzle 46 can also be used to direct (or focus) the solvent spray as it passes through the nozzle.

[0161] The sprayer assembly can be capable of producing a fine spray of solvent droplets, for example having a beam width of less than 50 pm at a distance of 1.5 mm from the front face of the nozzle 46.

[0162] As mentioned above, in various embodiments the assembly is configured such that installation of the nozzle 46 moves the sheath 31 relative to the capillary 32 to the second exposed position, and removal of the nozzle 46 moves the sheath 31 relative to the capillary 32 to the first protected position.

[0163] For example, with reference to Figure 4, the assembly can be configured such that removal of the nozzle 46 unloads the compression spring 33 and, in doing so, pushes the sheath 31 to extend over the outlet (solvent ejection tip) 32A of the capillary 32, thereby protecting the capillary 32 from damage. Conversely, when the nozzle 46 is installed, the nozzle 46 can push the sheath 31 such that the sheath 31 retracts to the exposed position, and the compression spring 33 is compressed. The sheath can then be held in the retracted position by connecting the nozzle 46 to the manifold body 41. This then means that the capillary outlet (tip) 32A can be protected by the sheath 31 when the nozzle 46 is removed, and the sheath 31 is able to retract to allow normal use when the nozzle 46 is installed.

[0164] As can be seen in Figure 4A The assembly can be configured such that, when the capillary 32 and nozzle 46 are installed, the capillary 32 and nozzle 46 are arranged coaxially relative to each other such that the outlet (tip) 32A of the capillary 32 is aligned (in line) with the bore 46C of the nozzle 46. The inventors have found that the spray can be particularly sensitive to the alignment (centring) of the outlet (solvent ejection tip) 32A of the capillary 32 with the bore 46C of the nozzle 46, and so spray reproducibility can be improved by ensuring that the alignment (centring) between the nozzle bore 46C and the capillary outlet (tip) 32A is highly reproducible.

[0165] This can be implemented in any suitable way. In embodiments, the assembly is configured with nozzle guides that direct the nozzle 46 to align coaxially with the capillary outlet (tip) 32A when the nozzle 46 is installed. This can help to ensure that the bore 46C of the nozzle 46 is centrally and reproducibly positioned relative to the outlet (tip) 32A of the capillary 32.

[0166] For example, as can be seen best in Figure 4A and Figure 4D the nozzle 46 can comprise a rear aperture 46B configured to fit coaxially over an end (outlet end) of the sheath 31. The aperture and sheath end can each be generally cylindrical, although other shapes would be possible. As described above, the capillary 32 can be disposed in a central axial aperture 31A that is in turn disposed in the sheath 31, and the nozzle bore 46C can be located on a central axis of the nozzle 46 such that, when the rear aperture 46B is fitted coaxially over the end of the sheath 31, the capillary outlet 32A and the nozzle bore 46C are aligned.

[0167] Accordingly, in various embodiments, installing the nozzle 46 involves sliding the rear nozzle aperture 46B over the end of the sheath 31. When the nozzle aperture 46B is fully located over the end of the sheath 31, further pressure applied to the nozzle 46 can cause the sheath 31 to retract from the protected position to the exposed position. A connector can connect the nozzle 46 to the manifold body 41 such that the sheath 31 is held in the retracted (exposed) position for use.

[0168] The nozzle connector can comprise a threaded connector. This arrangement can allow tool-free installation and removal of the sprayer assembly.

[0169] However, the inventors have recognised that the spray can be particularly sensitive to the distance between the nozzle bore 46C and the solvent discharge outlet 32A of the capillary. For example, it has been found that maintaining the solvent discharge outlet 32A of the capillary at a distance of around 0.5mm behind the nozzle bore 46C can improve the spray performance of the spray.

[0170] The inventors have furthermore recognised that there is a risk in the event that a user’s threaded connector does not screw the connector fully into place. Accordingly, the use of a threaded connector can increase the opportunity for variation in the nozzle bore to capillary outlet distance, which can be associated with a degradation in the reproducibility of the spray.

[0171] In various embodiments, the nozzle connector is a bayonet connector. Bayonet connectors can also be referred to as “¼ turn” and / or “BNC” connectors. The inventors have found that the use of such connectors can reduce the risk of variation in the nozzle bore to capillary outlet distance, and so can improve the reproducibility of the spray, for example compared to a threaded connector.

[0172] Figure 4A - E illustrates a bayonet connector according to various embodiments. As can be seen most clearly in Figure 4E The nozzle 46 can be provided as part of a nozzle assembly comprising a male connector comprising a barrel 47A and two lugs 47B protruding radially inward from the rear of the barrel 47A.

[0173] As can be seen most clearly in Figure 4C The manifold body 41 can comprise a complementary female connector comprising a body 47C having two grooves 47D complementary to the two lugs 47B.

[0174] The connection can be made by pushing the barrel 47A over the connector body 47C with the lugs 47B aligning into and passing along the grooves 47D. Then, when the lugs 47B pass beyond the rear surface of the connector body 47C, the barrel 47A can be rotated (e.g. ¼ turn (90 degrees)) so that the lugs 47B can engage the rear surface of the connector body 47C.

[0175] Figure 4D The nozzle assembly of the present embodiment is shown in more detail. The nozzle assembly comprises a nozzle 46 and a nozzle connector barrel 47A. The nozzle can be held captive to the barrel 47A, for example between a nozzle retaining clip 46A provided on the nozzle 46 and a spring washer 48.

[0176] Providing the nozzle and nozzle connector as separate elements allows the nozzle to be interchangeably replaced without having to replace the nozzle connector. However, it is also envisaged that the nozzle and nozzle connector can be integrated.

[0177] As can be seen in Figure 4A When the nozzle 46 is connected to the manifold body 41, the nozzle 46 can be held in position between the front face of the connector body 47C and the spring washer 48. The inventors have found that this arrangement can allow a highly reproducible capillary exit to nozzle bore distance to be achieved.

[0178] Various alternative embodiments are illustrated in Figures 5 to 7.

[0179] Whilst in the above described embodiments the compression spring 33 is provided within the cavity 31B of the sheath 31, Figures 5 and 6 show embodiments in which the compression spring 33 is provided externally of the sheath 31. As can be seen in Figures 5 and 6, in these embodiments the compression spring 33 can be compressed between a collar 32B provided on the capillary tube and the (external) end of the sheath 31.

[0180] While in the above embodiments the end of the retractable sheath 31 acts as a nozzle guide to guide the nozzle 46 into coaxial alignment with the capillary tube 32, it is also possible to provide a separate nozzle support 52 to guide the nozzle 46 into coaxial alignment with the capillary tube 32. For example, FIG. 7 illustrates an embodiment in which the nozzle support 52 is configured to guide the nozzle 46 into coaxial alignment with the capillary tube 32 when the nozzle 46 is installed. Figure 5A and FIG. 7 illustrate embodiments in which the nozzle support 52 acts as a nozzle guide. For example, FIG. 7 illustrates an embodiment in which the nozzle support 52 is configured to guide the nozzle 46 into coaxial alignment with the capillary tube 32 when the nozzle 46 is installed. In these embodiments, the nozzle support 52 is configured to hold the capillary tube 32 and / or the sheath 31 centered to the nozzle support 52 such that the nozzle aperture 46C is aligned with the capillary tube outlet 32A when the nozzle 46 is attached to the nozzle support 52. Figure 5A and FIG. 7 illustrate embodiments in which the nozzle support 52 acts as a nozzle guide. For example, FIG. 7 illustrates an embodiment in which the nozzle support 52 is configured to guide the nozzle 46 into coaxial alignment with the capillary tube 32 when the nozzle 46 is installed. In these embodiments, the nozzle support 52 is configured to hold the capillary tube 32 and / or the sheath 31 centered to the nozzle support 52 such that the nozzle aperture 46C is aligned with the capillary tube outlet 32A when the nozzle 46 is attached to the nozzle support 52.

[0181] While in the above embodiments the nozzle 46 is connected with a bayonet connector, FIGS. 5 and 7 illustrate embodiments in which the nozzle connector is a threaded connector. For example, as can be seen in FIG. 5, a cap 51 can be provided having threads configured to attach to complementary threads on the nozzle support 52.

[0182] While in the above embodiments the nozzle 46 is separable from the nozzle connector, FIG. 6 illustrates an embodiment in which the nozzle and connector are integrated. Figure 7A FIG. 6 illustrates an embodiment in which the nozzle and connector are integrated.

[0183] While in the above embodiments the sheath 31 is able to be inserted into the manifold body 41 as a cartridge and held there by connecting the nozzle 46 to the manifold body 41, FIG. 6 illustrates an embodiment in which the sprayer assembly 60 is removably attached to a manifold assembly 61. In this embodiment, the sprayer assembly 60 includes one or more fasteners for removably mounting the sprayer assembly 60 to the manifold assembly 61, which can be in the form of one or more externally threaded connectors 67A, 67B.

[0184] In various embodiments, the manifold assembly 61 is configured with various input ports that can be coupled to the sprayer assembly 60 when the sprayer assembly 60 is connected to the manifold assembly 61.

[0185] Thus, as can be seen in FIG. 6, the manifold assembly 61 can include an input solvent port 63A for receiving an input solvent stream, and a solvent output port including a fluid seal 63B to provide solvent to a solvent input 63C of the sprayer assembly 60 when the sprayer assembly 60 and manifold assembly 61 are connected.

[0186] The manifold assembly 61 can also comprise an input gas port 62A for receiving an input gas stream, and a gas output end comprising a gas seal 62B to provide gas to a gas input end 62C of the sprayer assembly 60 when the sprayer assembly 60 and manifold assembly 61 are connected.

[0187] The manifold assembly 61 can also comprise an input high voltage pin 64A for receiving an input high voltage, and an output high voltage pin 64B for providing high voltage to a high voltage input end (not shown) of the sprayer assembly 60 when the sprayer assembly 60 and manifold assembly 61 are connected.

[0188] Figure 6C - Figure E shows a cross-sectional view of the sprayer assembly 60 of the present embodiment. Figure 6C is an exploded view of the sprayer assembly 60, Figure 6D shows the sprayer assembly 60 with the nozzle 46 removed and the sheath 31 positioned in a protective position, and Figure 6E shows the sprayer assembly 60 with the nozzle 46 attached and the sheath 31 in a retracted (exposed) position.

[0189] As mentioned above, the inventors have recognised that the spray can be particularly sensitive to the distance between the nozzle orifice 46C and the solvent ejection outlet 32A of the capillary tube. Accordingly, in some embodiments (as mentioned above) it can be desirable to configure the sprayer assembly such that variations in the nozzle orifice to capillary outlet distance are reduced or minimised.

[0190] An alternative approach is to configure the sprayer assembly such that (in use) the nozzle orifice to capillary outlet distance can be adjusted in a controllable manner. In other words, the sprayer assembly can be configured to enable a user to (in use) controllably adjust the nozzle orifice to capillary outlet distance in order to obtain a desired spray performance. This means that the nozzle orifice to capillary outlet distance can be set precisely to a desired value, and / or can allow for relaxation of manufacturing tolerances of the sprayer assembly without introducing uncontrolled variations in the nozzle orifice to capillary outlet distance.

[0191] Accordingly, in various embodiments the sprayer assembly is configured such that the distance between the nozzle orifice 46C and the capillary outlet 32A is adjustable (when the sprayer assembly is in use). The distance between the nozzle orifice 46C and the capillary outlet 32A can be adjusted in a controllable manner, i.e. such that when the distance between the nozzle orifice 46C and the capillary outlet 32A is set (by a user) at a particular value, the distance between the nozzle orifice 46C and the capillary outlet 32A remains at that particular value (when the sprayer assembly is used to generate a spray).

[0192] The sprayer assembly can be configured such that the distance between the nozzle aperture 46C and the capillary outlet 32A is controllably adjustable in any suitable manner. For example, in various particular embodiments, portions of all of the rear surface of the connector body 47C (as described above with reference to Figure 4C the connector body 47C can be beveled (inclined) and / or curved with respect to the (vertical) front surface of the connector body 47C.

[0193] Figure 8 A side view of the manifold body 41 and the connector body 47C configured in accordance with these embodiments is shown. As Figure 8 shown, the manifold body 41 and the connector body 47C can be configured in a similar manner to that described above. Thus, a first (distal front) surface 47E of the connector body 47C can be parallel to the face of the manifold body 41 (these surfaces can be configured to be generally perpendicular in use). The connector body 47C also has a second (rear) surface 47F configured to engage the lugs 47B of the barrel 47A of the nozzle assembly when the nozzle assembly is mounted on the manifold body 41 (as described above).

[0194] However, in contrast to the embodiments described above, the second (rear) surface 47F of the connector body 47C can not be parallel to the first surface 47E (and to the face of the manifold body 41), for example such that the second surface 47F is beveled, inclined and / or generally non-perpendicular in use. The second surface 47F will also have a curved shape, such as a cam shape. When the nozzle assembly is mounted on the connector body 47C (as described above), the lugs 47B will engage the second surface 47F (due to the force from the compression spring 33), such that as the barrel 47A is rotated, the distance between the nozzle aperture 46C and the capillary outlet 32A will controllably change.

[0195] Various other configurations for the sprayer assembly will be possible, such that the distance between the nozzle aperture 46C and the capillary outlet 32A is controllably adjustable.

[0196] In embodiments, the distance between the nozzle aperture 46C and the capillary outlet 32A can be adjustable by any suitable (relatively small) amount. For example, in embodiments, the distance between the nozzle aperture 46C and the capillary outlet 32A can be adjustable by about < 500 pm; < 400 pm; < 300 pm; < 200 pm; or < 100 pm.

[0197] In various particular embodiments, the second surface 47F is angled such that a maximum rotation of the barrel 47A (for example by about 180°) causes the distance between the nozzle aperture 46C and the capillary outlet 32A to be adjusted by about 200 pm.

[0198] Figure 9A andFigure 9B A spray tip assembly constructed in accordance with further embodiments is shown. In these embodiments, in addition to one or more lugs 47B, the spray tip assembly can also include one or more stops (or "flags") 47G. The stops 47G can project axially inwardly from the rear of the barrel 47A.

[0199] When the spray tip assembly is mounted on the manifold body 41, the stops 47G can be configured to limit rotation of the barrel 47A. For example, the stops 47G can be configured such that interaction of the stops 47G with the inner wall of one or more of the grooves 47D (as described above) prevents rotation of the barrel 47A beyond a certain maximum rotation angle. It is possible, for example, to provide such stops 47G in any of the above-described embodiments with respect to Figure 4A -E and / or Figure 8 such stops 47G in order to precisely limit rotational movement of the barrel 47A when the barrel 47A is mounted on the manifold body 41.

[0200] Although, as shown above, in particular as shown in Figure 4A and Figure 4D shown above, the rear orifice 46B of the spray tip 46 (and the outlet end of the sheath 31) can have a generally cylindrical shape, the inventors have found that different shapes can provide improved alignment (centering) of the outlet (solvent discharge tip) 32A of the capillary 32 with the bore 46C of the spray tip 46.

[0201] For example, as shown in Figure 10 the rear orifice 46B of the spray tip 46 (at least portions thereof) can have a conical or frustoconical shape, and the outlet end of the sheath 31 can have a complementary conical or frustoconical shape. In these embodiments, interaction of the (frusto)conical outer surface of the outlet end of the sheath 31 with the (frusto)conical inner surface of the rear orifice 46B of the spray tip 46 (as a result of the heat caused by the force of the compression spring 33 when the spray tip 46 is mounted on the sheath 31) causes the outlet (solvent discharge tip) 32A of the capillary 32 (which is held by the sheath 31) to be concentrically aligned with the bore 46C of the spray tip 46. This arrangement has been found to significantly improve concentric alignment of the discharge and spray tip bore.

[0202] Although, as described above (with reference to Figures 3A-3E ), the sheath 31 can be formed as a single part having axial orifices 31A, 31B and one or more gas conduits 36C which can run along and parallel to a length of the axial orifices, in further embodiments the sheath 31 can be formed from multiple parts. For example, this can increase the ease of manufacturability of the sheath 31. For example, this can allow one or more of the multiple parts to be formed by injection moulding.

[0203] Figure 11A An end view is shown, andFigure 11B A side cross-sectional view of a sheath 31 constructed in accordance with these embodiments is shown. As Figure 11A and Figure 11B shown, the sheath 31 can be formed from a (outer) main sheath body 31D and a sheath insert 31E. The axial bore of the main sheath body 31D can be configured to receive and retain the sheath insert 31E. One or both of the main sheath body 31D and the sheath insert 31E can be formed by injection molding.

[0204] In these embodiments, the second axial segment or cavity 31B can be formed in the main sheath body 31D (similar to the above-described embodiments), but the first axial segment 31A (which is configured and dimensioned to retain the capillary 32) and the one or more gas conduits 36C can be formed in the sheath insert 31E.

[0205] Thus, the sheath insert 31E can include a central axial bore 31A (which is configured and dimensioned to retain the capillary 32) and the one or more gas conduits 36C. As Figure 9A and Figure 9B shown, the one or more gas conduits 36C can be formed as one or more (open- sided) grooves in the sheath insert 31E. It would also be possible for one or more of the one or more gas conduits 36C to be formed as a bore in the sheath insert 31E.

[0206] Other arrangements would be possible.

[0207] In various embodiments, a spray of charged droplets produced by a sprayer assembly as described above is directed toward a sample. The spray can desorb analyte material from the surface of the sample, which can then be transported to an analytical instrument, such as a mass and / or ion mobility spectrometer, for analysis. The ions can then be analyzed to determine their mass-to-charge ratios and / or ion mobilities, and / or to determine mass-to-charge ratios and / or ion mobilities of ions derived from the original ions (e.g., by fragmentation of the original ions), etc.

[0208] While the above-described examples are particularly directed to desorption electrospray ionization (“DESI”) systems, it will be appreciated that the features described herein can relate generally to various types of (ambient) ion sources. For example, various DESI-derived techniques have been developed and the techniques presented herein can be equally applied to these techniques.

[0209] While the application has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the application as set forth in the following claims.

Claims

1. A sprayer assembly comprising: a capillary tube having an outlet; a sheath for the capillary tube; and a resilient member; wherein the assembly is configured such that the sheath is movable relative to the capillary tube between a first position in which the sheath covers the outlet of the capillary tube and a second position in which the outlet of the capillary tube is uncovered by the sheath; wherein the assembly is configured such that the resilient member provides a restoring force to restore the position of the sheath to or towards the first position when the sheath is moved from the first position to or towards the second position; wherein the sheath comprises one or more gas inlets, one or more gas outlets, and one or more gas conduits connecting the one or more gas inlets to the one or more gas outlets; and wherein the assembly is configured such that gas provided to the one or more gas inlets is emitted from the one or more gas outlets so as to atomise liquid emitted from the outlet of the capillary tube.

2. The assembly of claim 1, wherein the resilient member is held in a cavity within the sheath.

3. The assembly of claim 1 or 2, wherein the resilient member comprises a compression spring.

4. The assembly of any preceding claim, wherein: the sheath comprises an axial aperture configured to hold the capillary tube; and the one or more gas conduits are each arranged parallel to the axial aperture.

5. The assembly of any preceding claim, further comprising a sprayer assembly body; wherein the capillary tube, the sheath and the resilient member are removably attached to the body.

6. The assembly of claim 5, wherein: the capillary tube, the sheath and the resilient member are configured as a cartridge; and the cartridge is removably attached to the body.

7. The assembly of claim 6, wherein the body comprises an aperture configured to house the cartridge.

8. The assembly of claim 5, 6 or 7, further comprising a nozzle removably attached to the body; wherein the nozzle comprises an aperture and wherein the assembly is configured such that liquid emitted from the outlet of the capillary tube is directed through the aperture when the nozzle is attached to the body.

9. The assembly of claim 8, wherein the sprayer assembly is configured such that a distance between the aperture and the outlet of the capillary tube is adjustable.

10. The assembly of claim 8 or 9, wherein the assembly is configured such that attaching the nozzle to the body moves the sheath to the second position and such that removing the nozzle from the body moves the sheath to the first position.

11. The assembly of claim 10, wherein the assembly is configured such that the nozzle pushes the sheath to the second position when the nozzle is attached to the body. ​ 12. The assembly of any of claims 8 to 11, wherein the sheath is configured as a nozzle guide such that, when the nozzle is attached to the body, the guide directs the nozzle to be coaxially aligned with the capillary.

13. A sprayer assembly, the sprayer assembly comprising: a sprayer assembly body; and a cartridge, the cartridge housing a capillary, the capillary having an outlet from which liquid is emitted; wherein the cartridge comprises: a sheath for the capillary; and a resilient member; wherein the cartridge is configured such that the sheath is movable relative to the capillary between a first position in which the sheath covers the outlet of the capillary and a second position in which the outlet of the capillary is uncovered by the sheath; wherein the cartridge is configured such that, when the sheath is moved from the first position towards or towards the second position, the resilient member provides a restoring force to restore the position of the sheath to or towards the first position; the sprayer assembly further comprising: a nozzle, the nozzle being removably attachable to the sprayer assembly body; wherein the nozzle comprises an aperture; and wherein the sprayer assembly is configured such that attachment of the nozzle to the sprayer assembly body is capable of retaining the cartridge within the sprayer assembly body such that liquid emitted from the outlet of the capillary is directed through the aperture of the nozzle.

14. The assembly of claim 13, wherein: the body comprises one or more supply ports; and the assembly is configured such that, when the cartridge is retained within the body, the one or more supply ports are coupled to one or more corresponding ports of the cartridge.

15. The assembly of claim 13 or 14, wherein the nozzle is attachable to the body by a threaded or bayonet fitting.

16. The assembly of any of the preceding claims, wherein the assembly is a desorption electrospray ionisation (DESI) sprayer assembly.

17. An ion source comprising the sprayer assembly of any of the preceding claims.

18. A method of producing a spray of droplets, the method comprising using the sprayer assembly of any of claims 1 to 16 to produce a spray of droplets.

Images