Abstract:
An apparatus for connecting an ionisation probe assembly to a mass and/or ion mobility spectrometer is disclosed. The apparatus comprises: an attachment member for releasably attaching a probe assembly to the apparatus; a cap for enclosing the attachment member; wherein the apparatus is operable to deliver a voltage to a probe assembly only when the cap is arranged to enclose the attachment member; and wherein the cap is configurable to enclose the attachment member when a probe assembly is attached to the apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from and the benefit of United Kingdom patent application No. 1606124.4 filed on 11 Apr. 2016, and United Kingdom patent application No. 1606123.6 filed on 11 Apr. 2016. The entire content of these applications is incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates generally to mass and/or ion mobility spectrometers, and in particular to apparatus for coupling chromatography systems with ion sources and/or mass and/or ion mobility spectrometers. 
       BACKGROUND 
       [0003]    Liquid chromatography systems are an important tool to the analytical chemist for the separation and analysis of samples of interest. Often, after separation in the liquid chromatograph, the components require further analysis to confirm the identity of these components. This may be performed using a mass and/or ion mobility spectrometer. However, connecting liquid chromatography systems to mass and/or ion mobility spectrometers can be a difficult and time consuming task. 
         [0004]    Tubing may be used to deliver eluent to an ion source, wherein the eluent from the liquid chromatography system is sprayed into the ion source chamber through a capillary. This can result in an awkward connection that requires dexterity and skill to assemble. Moreover, there is a risk of electric shock at the connection for the user assembling the instrument connection, especially if there is a leak. The connecting assembly can also be expensive. 
         [0005]    Furthermore, the fitting of the liquid chromatography tube connection into an ion source can take a long time, resulting in inactivity of the instrument. Poor instrument performance may also occur if parts are omitted or poorly assembled. This can result in dead volumes, which may lead to poor reproducibility or poor performance of the instrument. 
         [0006]    The Applicant&#39;s earlier application GB-2520389 addresses these and other problems by providing a probe assembly for delivering eluent to a mass spectrometer, wherein a joint between an electrically insulated liquid line and a conductive capillary is provided downstream of an attachment device that attaches the probe to the spectrometer. This means that the eluent is less likely to leak out of the spectrometer when the probe is attached. A conductive member is provided in order to supply a voltage from the attachment device, downstream beyond the insulated liquid line and to the conductive capillary. This enables a voltage to be supplied relatively easily from the mass spectrometer to the conductive capillary via the attachment device, even though the electrically insulated liquid line is interposed between the attachment device and the conductive capillary. The structure of the probe therefore enables the electrical connection to be made between the spectrometer and the conductive capillary relatively quickly and easily. 
         [0007]    Notwithstanding the benefits associated with the probe assembly described in GB-2520389, the Applicants believe that there remains scope for further improvements to mass and/or ion mobility systems in which an atmospheric pressure ionisation probe is coupled with mass and/or ion mobility spectrometer. 
         [0008]    It is therefore desired to provide improved apparatus for mass and/or ion mobility spectrometry. 
       SUMMARY 
       [0009]    According to a first aspect there is provided apparatus for connecting an ionisation probe assembly to a mass and/or ion mobility spectrometer, the apparatus comprising: 
         [0010]    an attachment member for releasably attaching a probe assembly to the apparatus; 
         [0011]    a cap for enclosing the attachment member; 
         [0012]    wherein the apparatus is operable to deliver a voltage to a probe assembly only when the cap is arranged to enclose the attachment member; and 
         [0013]    wherein the cap is configurable to enclose the attachment member when a probe assembly is attached to the apparatus. 
         [0014]    The cap may be configurable to enclose the attachment member when no probe assembly is attached to the apparatus (e.g. when the probe assembly is detached from the apparatus), e.g. so as to prevent a probe assembly or other object being brought into contact with the attachment member. 
         [0015]    According to a second aspect there is provided apparatus for connecting an ionisation probe assembly to a mass and/or ion mobility spectrometer, the apparatus comprising: 
         [0016]    an attachment member for releasably attaching a probe assembly to the apparatus; 
         [0017]    a cap for enclosing the attachment member; 
         [0018]    wherein the cap is configurable to enclose the attachment member when a probe assembly is attached to the apparatus; and 
         [0019]    wherein the cap is configurable to enclose the attachment member when no probe assembly is attached to the apparatus (e.g. when the probe assembly is detached from the apparatus) e.g. so as to prevent a probe assembly or other object being brought into contact with the attachment member. 
         [0020]    According to various embodiments, apparatus is provided for connecting an ionisation probe assembly to a mass and/or ion mobility spectrometer. The apparatus may comprise an attachment member for releasably attaching the probe assembly to the apparatus and a cap for enclosing the attachment member, i.e. for preventing access to the attachment member. The apparatus may be operable to deliver a voltage to a probe assembly, e.g. via the attachment member, only when the cap is arranged to enclose the attachment member. The cap may be configurable to enclose the attachment member when a probe assembly is attached to the apparatus. The cap may be configurable to enclose the attachment member when no probe assembly is attached to the apparatus so as to prevent a probe assembly being brought into contact with the attachment member. 
         [0021]    Accordingly, the risk of electrocution, the risk of a user coming into contact with potentially hazardous substances that may leak from the attachment member, the risk of leaks adversely affecting the instrument, and/or fire hazard risks are substantially reduced, both when a probe assembly is attached to the apparatus and/or when no probe assembly is attached to the apparatus. 
         [0022]    It will be appreciated therefore that various embodiments described herein provide improved apparatus for mass and/or ion mobility spectrometry. 
         [0023]    The apparatus may comprise an orifice. 
         [0024]    The apparatus may be configured such that the probe assembly is insertable into the orifice 
         [0025]    The attachment member may be configurable to releasably secure the probe assembly within the orifice. 
         [0026]    The attachment member may comprise or may be in electrical communication with an electrical contact for delivering the voltage from the apparatus to the probe assembly when the probe assembly is releasably attached to the apparatus. 
         [0027]    The cap may comprise an aperture through which at least a portion of the probe assembly can pass. 
         [0028]    The apparatus may comprise a device configured to close the aperture when the cap is arranged to enclose the attachment member and when no probe assembly is attached to the apparatus. 
         [0029]    The device may be configured such that the aperture is openable only when the attachment member is not (is other than) enclosed by the cap. 
         [0030]    The device may comprise one or more balls or other objects and one or more pockets for receiving the one or more balls or other objects. 
         [0031]    The apparatus may comprise a probe tip configured to receive a capillary of the probe assembly. 
         [0032]    The apparatus may comprise a device for controlling the position of the capillary relative to the probe tip. 
         [0033]    The device may be configured such that the position remains substantially unaltered when a probe assembly is detached from and/or attached to the apparatus. 
         [0034]    According to an aspect there is provided apparatus for connecting an ionisation probe assembly to a mass and/or ion mobility spectrometer, the apparatus comprising: 
         [0035]    an attachment member for releasably attaching a probe assembly to the apparatus; 
         [0036]    a probe tip configured to receive a capillary of the probe assembly; and 
         [0037]    a control device for controlling the position of the capillary relative to the probe tip. 
         [0038]    The device may be configured such that the position remains substantially unaltered when a probe assembly is detached from and/or attached to the apparatus. 
         [0039]    The probe tip may comprise a capillary configured to receive the capillary of the probe assembly. 
         [0040]    The control device may be configured to control the position of the capillary relative to the probe tip capillary. 
         [0041]    The apparatus may comprise a guiding member configured to guide the capillary into the probe tip capillary when the probe assembly is releasably attached to the apparatus. 
         [0042]    The apparatus may comprise a cap for enclosing the attachment member. 
         [0043]    The attachment member may be provided in a main body of the apparatus. 
         [0044]    The cap may be releasably securable to the main body so as to enclose the attachment member. 
         [0045]    The control device may be operable from an external surface of the cap. 
         [0046]    The control device may comprise a first mechanism in the cap that is engagable with a second mechanism in the main body. 
         [0047]    Operation of the control device may cause the position of the capillary relative to the probe tip to be altered via the first and second mechanisms. 
         [0048]    The first and/or second mechanisms may be configured such that the position of the capillary relative to the probe tip remains substantially unaltered when the cap is secured to and/or released from the main body. 
         [0049]    The apparatus may comprise a liquid drain. 
         [0050]    The apparatus may comprise a device for collecting liquid incident upon at least a portion of the apparatus and for directing the liquid to the drain. 
         [0051]    The drain may comprise one or more open-ended slots or indentations. 
         [0052]    According to an aspect, there is provided apparatus for connecting an ionisation probe assembly to a mass and/or ion mobility spectrometer, the apparatus comprising: 
         [0053]    an attachment member for releasably attaching a probe assembly to the apparatus; 
         [0054]    a liquid drain; and 
         [0055]    a device for collecting liquid incident upon the apparatus and for directing the liquid to the liquid drain; 
         [0056]    wherein the drain comprises one or more open-ended slots or indentations. 
         [0057]    The apparatus as may comprise one or more fins, ridges, bumps or other protrusions configured to prevent blockage of the drain. 
         [0058]    The position and/or orientation of the drain may be fixed. 
         [0059]    According to an aspect there is provided an adaptor for connecting a ionisation probe assembly to a mass and/or ion mobility spectrometer, the adaptor comprising apparatus as described above. 
         [0060]    According to an aspect there is provided a mass and/or ion mobility spectrometer comprising apparatus as described above. 
         [0061]    According to an aspect there is provided a method of delivering eluent to a mass and/or ion mobility spectrometer comprising: 
         [0062]    providing a probe assembly; 
         [0063]    providing apparatus as described above; 
         [0064]    releasably attaching the probe assembly to the apparatus using the attachment member; and 
         [0065]    supplying eluent to the probe assembly such that eluent is transmitted through the probe assembly into the spectrometer. 
         [0066]    The probe assembly may comprise: 
         [0067]    an inlet for receiving an eluent from a chromatography device; 
         [0068]    an outlet for delivering the eluent to an ion source of a mass and/or ion mobility spectrometer; and 
         [0069]    an attachment device for attaching the outlet to the apparatus. 
         [0070]    The outlet may comprise a (optionally electrically conductive) capillary and a (optionally electrically conductive) member surrounding at least part of the capillary. 
         [0071]    The probe assembly may comprise a (optionally electrically insulating) liquid line for transporting eluent from the inlet to the capillary and a joint between the liquid line and the capillary, wherein the joint is downstream of the attachment device. 
         [0072]    The member may be arranged to receive a voltage upon connection of the attachment device to the apparatus and the member may be arranged to be in electrical connection with the capillary. 
         [0073]    The outlet of the probe assembly may be configured to be insertable into an orifice of the apparatus and the attachment device may be configured so as to releasably engage the orifice so as to releasably attach the probe to the apparatus. 
         [0074]    The joint may be arranged in the probe so as to be downstream of the orifice (i.e. within the apparatus) when the attachment device is connected to the apparatus. 
         [0075]    It will be appreciated that the term “downstream” used herein refers to the direction from the inlet end to the outlet end of the probe assembly and/or adaptor. 
         [0076]    The attachment device may comprise a screw fitting, a clamp, a bayonet or any other suitable type of attachment. 
         [0077]    The screw fitting may comprise threads that extend circumferentially around the liquid line for engaging an orifice in the apparatus into which the probe is inserted, in use. The screw fitting and threads may be on an outer surface of the attachment device. Alternatively, the releasable engagement may be provided by other attachment means, or any form of attachment means which does not require tools to fit. 
         [0078]    The attachment device may comprise a first electrical contact for receiving the voltage from the apparatus when the attachment device is releasably connected thereto, wherein the electrical contact is connected to the member and the member is connected to the capillary for transmitting the voltage from the apparatus to the capillary. The electrical contact may be on an outer surface of the attachment device. 
         [0079]    The electrical contact may be a ferrule. 
         [0080]    The electrical contact (e.g. ferrule) may be an integral or non-integral part of the attachment device. The electrical contact may form part of the attachment device such that when the attachment device is releasably connected to the apparatus, the electrical contact is connected to the apparatus and the member for transmitting the voltage from the spectrometer to the capillary. 
         [0081]    The member may surround the joint. The member may be able to transmit the voltage from the attachment device, downstream of the liquid line and to the capillary. 
         [0082]    The member may be a (optionally electrically conductive) tube. The tube may extend from being in contact with the electrical contact on the attachment device to being in contact with the capillary. 
         [0083]    The electrical connection from the member to the capillary may be performed by tabs in the member; and/or the electrical connection from the member to the capillary may be performed by an electrically conductive packing between the member and the capillary. 
         [0084]    The member may be arranged to receive the voltage upon connection of the attachment device to the apparatus through an electrically conductive ferrule. 
         [0085]    The capillary may be configured to spray eluent from its outlet. 
         [0086]    The capillary may be configured so as to transmit the voltage to the eluent being sprayed therefrom for forming charged droplets of eluent. 
         [0087]    The capillary may be an electrospray capillary or an atmospheric pressure chemical ionisation capillary. 
         [0088]    The inlet for receiving the eluent may be spaced from the attachment device. 
         [0089]    The probe may have an inlet attachment device disposed towards one end of the probe and an outlet attachment device disposed towards the other end of the probe. 
         [0090]    The probe assembly may further comprise an inlet attachment device for attaching the inlet to a chromatography device. 
         [0091]    The inlet of the probe may be configured to be insertable into an orifice of the chromatography device and the inlet attachment device may be configured so as to releasably engage the orifice so as to releasably attach the probe to the chromatography device. 
         [0092]    The inlet attachment device may comprise a screw fitting, a clamp or a bayonet, or any other suitable type of attachment. The screw fitting may comprise threads that extend circumferentially about the liquid line for engaging an orifice in the chromatography device. The screw fitting and threads may be on an outer surface of the inlet attachment device. Alternatively, the releasable engagement may be provided by other attachment means, or any form of attachment means which does not require tools to fit. 
         [0093]    According to another aspect there is provided a mass and/or ion mobility spectrometer adapted to be connectable with a probe adaptor as described herein. 
         [0094]    According to another aspect there is provided a system comprising apparatus as described herein and the probe assembly described herein, wherein the outlet attachment device of the probe assembly and the apparatus are configured such that the outlet attachment device is releasably engagable with an orifice in the apparatus so as to connect the probe assembly to the apparatus with the probe assembly outlet inserted into the orifice. 
         [0095]    The apparatus of the system may comprise a voltage supply and a second electrical contact located proximate to the orifice for supplying the voltage to the capillary of the probe assembly. The second electrical contact may be arranged and configured such that when the outlet attachment device of the probe assembly is engaged with the orifice, the second electrical contact engages with the first electrical contact on the outlet attachment device for supplying the voltage from the voltage supply to the capillary. 
         [0096]    The apparatus may comprise a nebuliser tube and a gas supply for supplying gas through the nebuliser tube, and the probe outlet may be configured to be inserted through the orifice into the nebuliser tube. 
         [0097]    The system may comprise a chromatography device, wherein the probe assembly has a probe inlet configured to be releasably attached to the chromatography device so as to receive eluent from the chromatography device. 
         [0098]    The probe assembly may be arranged to receive eluent and deliver it through an orifice in a housing of a mass and/or ion mobility spectrometer. 
         [0099]    The probe assembly may comprise: 
         [0100]    a liquid line having a liquid inlet for receiving eluent; 
         [0101]    a capillary joined to the liquid line for receiving the eluent and having a liquid outlet for delivering the eluent into the spectrometer; 
         [0102]    an attachment member surrounding the liquid line, wherein the join between the liquid line and the capillary is located downstream of the attachment member, and wherein the attachment member is configured to releasably engage the apparatus when the capillary and part of the liquid line are inserted through said orifice; 
         [0103]    a first electrical contact on the attachment member for engaging an electrical contact on the apparatus when the capillary and liquid line are inserted through the orifice and the attachment member is releasably engaged with the apparatus; and 
         [0104]    a conductive member extending downstream from the electrical contact, passed the join between the liquid line and the capillary, and into contact with the capillary for supplying a voltage from the first electrical contact to the capillary. 
         [0105]    The join may be arranged in the probe so as to be downstream of the orifice when the attachment member is connected to the apparatus. 
         [0106]    The attachment member may comprise a screw fitting, a clamp, a bayonet, or any other suitable type of fitting for releasably engaging the apparatus when the capillary and liquid line are inserted through the orifice. 
         [0107]    The screw fitting may comprise threads that extend circumferentially around the liquid line for engaging an orifice in the apparatus into which the probe is inserted, in use. The screw fitting and threads may be on an outer surface of the attachment member. Alternatively, the releasable engagement may be provided by other releasable attachment means, or any form of attachment means which does not require tools to fit. 
         [0108]    The first electrical contact may be on an outer surface of the attachment member. The first electrical contact may be a ferrule. 
         [0109]    The electrical contact (e.g. ferrule) may be an integral or non-integral part of the attachment member. The electrical contact may form part of the attachment member such that when the attachment member releasably engages the apparatus, the electrical contact is connected to the apparatus and the member for transmitting the voltage from the apparatus to the capillary. 
         [0110]    The member may be a (optionally electrically conductive) tube that extends from the first electrical contact on the attachment member to the capillary. 
         [0111]    The electrical connection from the member to the electrically capillary may be performed by tabs in the member, and/or by an electrically conductive packing between the member and the capillary. 
         [0112]    The capillary may be configured to spray eluent from its outlet. 
         [0113]    The capillary may be configured so as to transmit the voltage to the eluent being sprayed therefrom for forming charged droplets of eluent. 
         [0114]    The capillary may be an electrospray capillary or an atmospheric pressure chemical ionisation capillary. 
         [0115]    The inlet for receiving the eluent may be spaced from the attachment member. 
         [0116]    The attachment member may be disposed towards an outlet end of the probe assembly and the probe assembly may have another attachment member disposed towards an inlet end of the probe assembly for attaching the inlet to a chromatography device or other source of analyte solution. 
         [0117]    The inlet of the probe may be configured to be insertable into an orifice of the chromatography device or other source of analyte solution and the inlet attachment member may be configured so as to releasably engage the orifice so as to releasably attach the probe assembly to the chromatography device or other source of analyte solution. 
         [0118]    The inlet attachment member may comprise a screw fitting, a clamp, a bayonet or any other suitable type of fitting. The screw fitting may comprise threads that extend circumferentially about the liquid line for engaging an orifice in the chromatography device or other source of analyte solution. The screw fitting and threads may be on an outer surface of the inlet attachment member. Alternatively, the releasable engagement may be provided by other attachment means, or any form of attachment means which does not require tools to fit. 
         [0119]    According to another aspect there is provided a system comprising apparatus and the probe assembly described herein, wherein the apparatus comprises a housing having an orifice therein for receiving the probe assembly therethrough, wherein the attachment member of the probe and the apparatus housing are configured such that the attachment member is releasably engagable with the orifice so as to connect the probe assembly to the apparatus with the capillary and part of the liquid line inserted through the orifice, wherein the apparatus comprises a voltage supply and a second electrical contact, and wherein the second electrical contact is arranged in the apparatus so as to engage the first electrical contact on the probe assembly when the probe assembly has been releasably engaged with the orifice. 
         [0120]    The orifice may be located in an adaptor or in an ion source of a mass and/or ion mobility spectrometer such that the capillary of the probe assembly extends into the ion source when the probe assembly is releasably engaged with the apparatus. 
         [0121]    The attachment member may have engaging elements that releasably engage with complementary engagement elements on the apparatus for enabling the releasable engagement of the probe assembly to the apparatus. 
         [0122]    The engaging elements on the attachment member may be screw threads and the engaging elements on the apparatus may be complementary screw threads. 
         [0123]    A seal may be provided on the attachment member and/or in the apparatus proximate the orifice for providing a liquid seal between the probe assembly and the apparatus when the probe assembly is releasably engaged with the apparatus. 
         [0124]    The apparatus may comprise a nebuliser tube and a gas supply for supplying gas through the nebuliser tube, and the probe outlet may be configured to be inserted through the orifice into the nebuliser tube. 
         [0125]    The system may comprise a chromatography device or other source of analyte solution or eluent, wherein the probe assembly may have a probe inlet configured to be attached to the chromatography device or other source so as to receive the solution or eluent. 
         [0126]    The inlet of the probe may be configured to be insertable into an orifice of the chromatography device or other source of analyte solution and the probe assembly may have an inlet attachment member configured so as to releasably engage the orifice so as to releasably attach the probe assembly to the chromatography device or other source of analyte solution. 
         [0127]    The inlet attachment member may have engaging elements that releasably engage with complementary engagement elements on the chromatography device or other source of analyte solution for enabling the releasable engagement of the probe assembly to the chromatography device or other source of analyte solution. The engaging elements on the attachment member may be screw threads and the engaging elements on the chromatography device or other source of analyte solution may be complementary screw threads. 
         [0128]    The inlet attachment member may comprise a screw fitting, a clamp, a bayonet or any other suitable type of fitting. The screw fitting may comprise threads that extend circumferentially about the liquid line for engaging an orifice in the chromatography device or other source of analyte solution. The screw fitting and threads may be on an outer surface of the inlet attachment member. Alternatively, the releasable engagement may be provided by other attachment means, or any form of attachment means which does not require tools to fit. 
         [0129]    According to another aspect, there is provided a method of delivering eluent to a mass and/or ion mobility spectrometer comprising: 
         [0130]    providing a system as described herein; 
         [0131]    inserting the outlet end of the probe assembly into the orifice; 
         [0132]    releasably engaging the attachment member of the probe assembly with the apparatus such that the first electrical contact of the probe assembly engages the second electrical contact of the apparatus; and 
         [0133]    supplying eluent into the liquid line such that the eluent is transmitted through the capillary and into the spectrometer. 
         [0134]    The method may comprise ionising the eluent or analyte solution in the spectrometer. 
         [0135]    The spectrometer may comprise one or more ion guides. 
         [0136]    The spectrometer may comprise one or more ion mobility separation devices and/or one or more Field Asymmetric Ion Mobility Spectrometer devices. 
         [0137]    The spectrometer may comprise one or more ion traps or one or more ion trapping regions. 
         [0138]    The spectrometer may comprise a mass analyser selected from the group consisting of: (i) a quadrupole mass analyser; (ii) a 2D or linear quadrupole mass analyser; (iii) a Paul or 3D quadrupole mass analyser; (iv) a Penning trap mass analyser; (v) an ion trap mass analyser; (vi) a magnetic sector mass analyser; (vii) Ion Cyclotron Resonance (“ICR”) mass analyser; (viii) a Fourier Transform Ion Cyclotron Resonance (“FTICR”) mass analyser; (ix) an electrostatic mass analyser arranged to generate an electrostatic field having a quadro-logarithmic potential distribution; (x) a Fourier Transform electrostatic mass analyser; (xi) a Fourier Transform mass analyser; (xii) a Time of Flight mass analyser; (xiii) an orthogonal acceleration Time of Flight mass analyser; and (xiv) a linear acceleration Time of Flight mass analyser. 
         [0139]    The spectrometer may comprise one or more energy analysers or electrostatic energy analysers. 
         [0140]    The spectrometer may comprise one or more ion detectors. 
         [0141]    The spectrometer may comprise one or more mass filters selected from the group consisting of: (i) a quadrupole mass filter; (ii) a 2D or linear quadrupole ion trap; (iii) a Paul or 3D quadrupole ion trap; (iv) a Penning ion trap; (v) an ion trap; (vi) a magnetic sector mass filter; (vii) a Time of Flight mass filter; and (viii) a Wien filter. 
         [0142]    The spectrometer may comprise a device or ion gate for pulsing ions; and/or a device for converting a substantially continuous ion beam into a pulsed ion beam. 
         [0143]    The spectrometer may comprise a C-trap and a mass analyser comprising an outer barrel-like electrode and a coaxial inner spindle-like electrode that form an electrostatic field with a quadro-logarithmic potential distribution, wherein in a first mode of operation ions are transmitted to the C-trap and are then injected into the mass analyser and wherein in a second mode of operation ions are transmitted to the C-trap and then to a collision cell or Electron Transfer Dissociation device wherein at least some ions are fragmented into fragment ions, and wherein the fragment ions are then transmitted to the C-trap before being injected into the mass analyser. 
         [0144]    The spectrometer may comprise a stacked ring ion guide comprising a plurality of electrodes each having an aperture through which ions are transmitted in use and wherein the spacing of the electrodes increases along the length of the ion path, and wherein the apertures in the electrodes in an upstream section of the ion guide have a first diameter and wherein the apertures in the electrodes in a downstream section of the ion guide have a second diameter which is smaller than the first diameter, and wherein opposite phases of an AC or RF voltage are applied, in use, to successive electrodes. 
         [0145]    The spectrometer may comprise a device arranged and adapted to supply an AC or RF voltage to the electrodes. 
         [0146]    A chromatography detector may be provided, wherein the chromatography detector comprises either: 
         [0147]    a destructive chromatography detector optionally selected from the group consisting of (i) a Flame Ionization Detector (FID); (ii) an aerosol-based detector or Nano Quantity Analyte Detector (NQAD); (iii) a Flame Photometric Detector (FPD); (iv) an Atomic-Emission Detector (AED); (v) a Nitrogen Phosphorus Detector (NPD); and (vi) an Evaporative Light Scattering Detector (ELSD); or 
         [0148]    a non-destructive chromatography detector optionally selected from the group consisting of: (i) a fixed or variable wavelength UV detector; (ii) a Thermal Conductivity Detector (TCD); (iii) a fluorescence detector; (iv) an Electron Capture Detector (ECD); (v) a conductivity monitor; (vi) a Photoionization Detector (PID); (vii) a Refractive Index Detector (RID); (viii) a radio flow detector; and (ix) a chiral detector. 
         [0149]    The spectrometer may be operated in various modes of operation including a mass spectrometry (“MS”) mode of operation; a tandem mass spectrometry (“MS/MS”) mode of operation; a mode of operation in which parent or precursor ions are alternatively fragmented or reacted so as to produce fragment or product ions, and not fragmented or reacted or fragmented or reacted to a lesser degree; a Multiple Reaction Monitoring (“MRM”) mode of operation; a Data Dependent Analysis (“DDA”) mode of operation; a Data Independent Analysis (“DIA”) mode of operation a Quantification mode of operation or an Ion Mobility Spectrometry (“IMS”) mode of operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0150]    Various embodiments will now be described, by way of example only, and with reference to the accompanying drawings in which: 
           [0151]      FIG. 1  shows schematically a probe assembly according to an embodiment; 
           [0152]      FIG. 2  shows schematically the outlet end of the probe assembly of  FIG. 1  for being fitted into a mass and/or ion mobility spectrometer; 
           [0153]      FIG. 3  shows schematically a detailed view of the outlet end of the probe showing the capillary and surrounding member; 
           [0154]      FIG. 4  shows schematically the inlet end of the probe assembly of  FIG. 1  for being fitted into a liquid chromatography device; 
           [0155]      FIGS. 5A and 5B  show schematically a probe adaptor in accordance with an embodiment; 
           [0156]      FIGS. 6A and 6B  show schematically a probe adaptor and a probe assembly in accordance with various embodiments; 
           [0157]      FIG. 7  shows the probe adaptor of  FIGS. 5A and 5B  installed in an ion source of a mass and/or ion mobility spectrometer; 
           [0158]      FIG. 8  shows schematically a probe adaptor and an installed probe assembly in accordance with an embodiment; 
           [0159]      FIG. 9  shows schematically a probe adaptor in accordance with an embodiment; 
           [0160]      FIGS. 10A and 10B  show schematically a conventional probe tip; 
           [0161]      FIG. 11  shows schematically the probe tip of the probe adaptor of  FIGS. 5A and 5B  in more detail; 
           [0162]      FIG. 12A  shows schematically an electrospray ionisation probe adaptor comprising in accordance an embodiment, and  FIG. 12B  shows schematically an atmospheric pressure ionisation probe adaptor comprising in accordance an embodiment; 
           [0163]      FIG. 13  shows schematically the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  in more detail; 
           [0164]      FIGS. 14A and 14B  show schematically a cut away view of the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  when the cap aperture is closed; 
           [0165]      FIG. 15  shows schematically a cut away view of the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B ; 
           [0166]      FIGS. 16A and 16B  show schematically a cut away view of the cap of the probe adaptor of  FIGS. 5A and 5B  when the cap aperture is open; 
           [0167]      FIG. 17  shows schematically a cut away view of the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  when the probe assembly of  FIG. 1  is installed in the adaptor; 
           [0168]      FIG. 18  shows schematically a cut away view of the adaptor of  FIG. 6 ; 
           [0169]      FIGS. 19, 20A, 20B, 20C, 21A, 21B, 22A and 22B  show schematically a cut away views of the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B ; 
           [0170]      FIGS. 23A and 23B  show schematically a cut away view of the adaptor of  FIG. 6 ; 
           [0171]      FIGS. 24A, 24B, and 24C  show schematically the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  when the probe assembly of  FIG. 1  is installed in the adaptor; 
           [0172]      FIGS. 25A, 25B, and 25C  show schematically the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  in more detail; 
           [0173]      FIGS. 26A and 26B  show schematically the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  when an object is inserted into the gutter; and 
           [0174]      FIGS. 27A and 27B  shows schematically the cap and main adaptor body of the probe adaptor of  FIGS. 5A and 5B  when the cap is opened. 
       
    
    
     DETAILED DESCRIPTION 
       [0175]    Various embodiments will now be described. Various embodiments described herein are directed to apparatus for coupling a liquid chromatography system and/or an ionisation probe assembly, e.g. an atmospheric pressure ionisation probe, with an ion source and/or mass and/or ion mobility spectrometer, e.g. with the ionisation chamber of a mass and/or ion mobility spectrometer. 
         [0176]    In general, the apparatus may be used for coupling any liquid based input with any spray ionisation process. For example, the liquid chromatography system may comprise any suitable liquid chromatography system such as a High Performance Liquid Chromatography (“HPLC”) system, Ultra Performance Liquid Chromatography (“UPLC”) system, convergence chromatography system, Supercritical Fluid Chromatography (“SFC”), and the like. Equally, the ion source may comprise any suitable ions source, such as an Electrospray Ionisation (“ESI”) ion source, an Atmospheric Pressure Chemical Ionisation (“APCI”) ion source, an impactor spray ion source, and the like. 
         [0177]    The apparatus may comprise an adaptor, i.e. a device that is releasably attachable to the spectrometer, e.g. by inserting the adaptor into an orifice of the (ionisation chamber of the) spectrometer. Additionally or alternatively, some or all parts of the apparatus may form part of the spectrometer, i.e. may be integrated with the spectrometer. 
         [0178]    The apparatus (i.e. the adaptor and/or spectrometer) may be configured such that the probe assembly is releasably attachable to the apparatus, e.g. by inserting the probe into an orifice of the apparatus. 
         [0179]      FIG. 1  shows a probe assembly  110  according to an embodiment. The probe assembly  110  has an inlet end  112  having an inlet attachment fitting  114  that is configured for attaching the probe to a liquid chromatography device (not shown). A liquid inlet  116  is located at the inlet end  112  of the probe and is arranged to be insertable into a liquid chromatography output (not shown) such that the liquid inlet  116  receives eluent from the liquid chromatography instrument. An (optionally electrically insulating) liquid line  118 , e.g. in the form of a silica capillary, runs from the liquid inlet  116  to an outlet end  120  of the probe. The inlet end  112  of the probe will be described in more detail in relation to  FIG. 4 . 
         [0180]      FIG. 2  shows the outlet end  120  of the probe assembly in more detail. In use, the outlet end  120  is inserted into the apparatus, e.g. into the adaptor or into the ion source of a mass and/or ion mobility spectrometer (not shown), and is releasably secured in the apparatus (adaptor or spectrometer) by the outlet attachment fitting  122 . The attachment fitting may comprise any suitable type of fitting, e.g. may comprise a screw threaded portion on its external surface that engages with and is screwed into a complementary screw thread on the adaptor or spectrometer, a ratchet fitting, a screw torque fitting, one or more clips, a bayonet fitting, one or more screws, and the like, for securing the probe to the adaptor or spectrometer and/or for preventing the incorrect fitting of the outlet attachment device (e.g. by over tightening it). 
         [0181]    The liquid line  118  runs from the liquid inlet  116  at the inlet end  112  to a (optionally electrically conductive) capillary  124  that forms a liquid outlet at the outlet end  120 . The capillary  124  may be formed, for example, from steel. The capillary  124  makes a joint (not shown) with the liquid line  118  at a location downstream of the outlet attachment fitting  122 . This is described in relation to  FIG. 3 . This arrangement may ensure that only electrically insulated tubing extends out of the adaptor or spectrometer from the attachment fitting  122 , thereby reducing the risk of electrocution of the user. 
         [0182]    The capillary  124  receives eluent from the liquid line  118  and delivers it into the spectrometer, when the outlet end  120  is attached to the spectrometer or adaptor (and the adaptor is attached to the spectrometer). 
         [0183]    In some embodiments, it may be desired to supply a voltage to the (e.g. electrically conductive) capillary  124  whilst spraying eluent into the spectrometer. However, in other embodiments, a voltage may not be provided to the capillary  124 . For example, the capillary  124  may be held at ground. 
         [0184]    Where a voltage is supplied to the capillary  124 , the voltage may be supplied by the adaptor or spectrometer to the outlet attachment fitting  122  and may then be conveyed from the outlet attachment fitting  122  to the capillary  124 . However, as mentioned above, the fluid line  118 , which may be electrically insulating, extends between the attachment fitting  122  and the capillary  124 . As such, an (optionally electrically conductive) member  126 , in the form of a tube, may be arranged to extend between an electrical connection on the attachment device  122  and the capillary  124 , e.g. so as to transmit a voltage from the attachment device  122  to the capillary  124 . The member  126  may cover the part of the liquid line  118  which passes downstream of the outlet attachment fitting  122 , the joint (not visible) and part of the capillary  124 . The end of the capillary  124  may be arranged to extend out from the (electrically conductive) tube  126 . A conductive ferrule  127  may form the electrical connection on the outlet attachment fitting  122  that provides an electrical connection between the adaptor or spectrometer and the tube  126 . An electrical connection (e.g. tabs  130 ) may also be arranged between the tube  126  and the capillary  124 , e.g. to allow the voltage to pass to the capillary  124 . 
         [0185]    A liquid bleed hole  129  may be provided in the member  126  for allowing liquid to bleed into the adaptor or spectrometer source if the joint between the capillary  124  and the liquid line  118  fails. This may prevent liquid bleeding out of the adaptor or spectrometer, which may be a potential source of electrocution or cause hazards to the user and/or instrument. 
         [0186]      FIG. 3  is a detailed cross-sectional illustration of a portion of the outlet end  120  of the probe assembly shown in  FIGS. 1 and 2 . The liquid line  118  may be joined to the capillary  124  at a joint  134  such that their bores are in fluid communication. The member  126  may extend from an electrical connection on the outlet attachment device  122  (not shown), over the joint  134  and into electrical connection with the capillary  124 . As such, a voltage can be supplied from the attachment device  122  to the capillary  124  by the member  126 , even though the fluid line  118  extends between the attachment device  122  and the capillary  124 . 
         [0187]    Metal tabs  130  may be cut into, or depressed in, the member  126 , e.g. so that these tabs  130  of the member  126  contact the capillary  124 . Where a voltage is supplied to the capillary  124 , this contact may make (and be used to provide) an electrical connection between the two components. 
         [0188]    Additionally or alternatively, the tabs  130  may be used in order to fix the capillary  124  in place relative to the member  126 . At least two tabs  130  may be provided, wherein one tab  130  may be forced into contact with one side of the capillary  124  and another tab  130  may be forced into contact with the other side of the capillary  124 . The tabs  130  may be arranged relatively close together at axially spaced apart locations. This arrangement serves to hold the capillary  124  in a substantially fixed radial position and ensures constant contact between the capillary  124  and the member  126 . 
         [0189]      FIG. 4  is a detailed view of the inlet end  112  of the probe assembly, i.e. the end to be fitted into the liquid chromatography system. As described in relation to  FIG. 1 , the inlet end  112  has an inlet attachment fitting  114  for attaching the probe to a liquid chromatography device (not shown). In use, the inlet end  112  of the probe may be inserted into the liquid chromatography device and releasably secured therein. The attachment device may include a fitting for engaging the liquid chromatography device so as to releasably secure the probe to the liquid chromatography device. Any suitable type of fitting may be provided, such as a screw threaded portion and/or ratchet mechanism for engaging a complementary profile on the liquid chromatography device, a screw torque fitting (e.g. for preventing the incorrect fitting of the outlet attachment device, e.g. by over tightening it), a bayonet fitting, one or more screws, one or more clips, and so on. 
         [0190]    A liquid inlet  116  at the inlet end  112  is arranged to receive the eluent from the liquid chromatography instrument. A liquid line  118  runs from the inlet end  116  to the outlet end  120 . 
         [0191]    The probe may have a range of variants suited to different applications. For example, the probe may be provided with different bore sizes for the liquid outlet diameter, different variations of the length of the capillary, different capillary sizes (diameters) and different lengths of liquid line, and so on. The position of the joint, the lengths of the liquid line  118 , member  126  and/or capillary  124 , etc. can be varied and selected as desired. 
         [0192]      FIGS. 5A and 5B  show a probe adaptor  200  in accordance with an embodiment, and  FIG. 7  shows the probe adaptor assembly  200  installed in an ion source  300  of a mass and/or ion mobility spectrometer in accordance with an embodiment.  FIGS. 6A and 6B  shows a probe adaptor  200  in accordance with another embodiment. 
         [0193]    As shown in  FIGS. 5A, 5B, and 6 , the adaptor  200  generally comprises a tube member  210 , a probe tip  220 , a main adaptor body  230  and a cap  240  that releasably engages with the main adaptor body  230 . The probe tip  220  is provided at the downstream end (i.e. the outlet end) of the tube member  210 , and the main adaptor body  230  is provided at the upstream end (i.e. the inlet end) of the tube member  210 . A part of the tube member  210 , e.g. its upstream (inlet) end, may be provided inside the main adaptor body  230   
         [0194]    The adaptor  200  is configured to be releasably secured to a mass and/or ion mobility spectrometer. In particular, as shown in  FIG. 7 , the adaptor  200  is configured to be insertable into an orifice of an ion source  300  of a mass and/or ion mobility spectrometer. When installed in the ion source  300 , the tube portion  210  and the probe tip  220  are enclosed within the ion source  300 , while the main adaptor body  230  and the cap  240  remain external to the ion source  300 . The adaptor may be secured to the spectrometer by securing the main adaptor body  230  to the spectrometer. 
         [0195]    As shown in  FIG. 7 , the adaptor  200  is configured such that when installed in the ion source  300 , at least a portion of the probe tip  220  extends into an ionisation chamber  310  of the ion source  300 . As will be described in more detail below, this allows eluent from the liquid chromatography system (not shown) to be sprayed into the ion source chamber  310  via the probe tip  220 . 
         [0196]    The adaptor  200  is further configured such that the outlet end  120  of a probe assembly can be inserted into an orifice in the adaptor  200 , and can be releasably secured in the adaptor using the outlet attachment fitting  122 . Accordingly, the adaptor  200  may comprise a complementary attachment fitting  231 , e.g. a screw fitting comprising a screw threaded portion that is configured to engage with the screw threaded portion of the attachment fitting  122  of the outlet end  120  of the probe assembly, when the probe assembly screw threaded portion engages with and is screwed into the adaptor screw fitting. Any other suitable type of complementary fitting may be provided, e.g. as described above. The attachment fitting  231  is provided in the main adaptor body  230  of the adaptor. 
         [0197]    The outlet attachment device  122  of the probe assembly  110  may comprise a housing and a cup  128 , such as a PEEK cup, for providing a sealing face between the attachment device  122  and the adaptor  200  when the attachment device is inserted into the adaptor  200 . The attachment device  122  may also comprise the ferrule  127  that may be used to make an electrical connection between the body of the adaptor (in which the probe is inserted) and the (conductive) member  126 . The ferrule  127  and the peek cup  128  may be crimped to the line  118  such that they do not move or rotate relative to the line  118 , capillary  124  or member  126 . The attachment device housing may be rotatable about and/or slidable along the line  118  for use in attaching the attachment device  122  to the adaptor  200 . The ferrule  127  and cup  128  may not rotate, but may sit in the housing. The attachment device housing may then be rotated so as to screw the attachment device  122  into the adaptor  200  so that the cup  128  forms a seal with the adaptor  200 . 
         [0198]    The adaptor  200  is configured such that when the outlet end  120  of the probe assembly is inserted into the adaptor  200  (via the orifice), the capillary  124 , the member  126 , the capillary joint  134  between the capillary  124  and the liquid line  118 , and part of the liquid line  118  are substantially enclosed within the main adaptor body  230  and the tube member  210 . 
         [0199]    In some embodiments, a portion of the capillary  124  will extend beyond the probe tip  220 , i.e. so that when the adaptor is installed in the ion source  200 , the capillary  124  will extend beyond the probe tip  220  into the ionisation chamber  310 . This may be the case, for example, where the ionisation source is an ESI ion source. In other embodiments, most or all of the capillary  124  may be enclosed within the tuber portion  210  and the probe tip  220 , i.e. so that the capillary  124  will not extend beyond the probe tip  220  into the ionisation chamber  310 . This may be the case, for example, where the ionisation source is an APCI ion source. 
         [0200]    A portion of the attachment fitting  122  will also extend beyond the adaptor main body  230  (proud of the orifice), together with the liquid line  118  and inlet portion  112  of the probe. 
         [0201]    In some embodiments, e.g. where the ionisation source is an ESI ion source, the tube member  210  of the adaptor  200  may comprise an internal nebuliser gas tube  211  that, when the probe assembly  110  is inserted into the adaptor  200  (via the orifice), surrounds the capillary  124 , the member  126 , the capillary joint  134  between the capillary  124  and the liquid line  118 , and part of the liquid line  118 . 
         [0202]    In use, eluent received from the liquid chromatography device passes from the liquid inlet  116  of the probe assembly, through the liquid line  118 , the capillary joint  134 , through the capillary  124 , to the liquid outlet  144 , and into the ionisation chamber  310  of the spectrometer. A nebuliser gas flow is arranged to flow along the nebuliser gas tube  211  of the tube member  210  towards the outlet of the capillary  124 . The gas flow will flow past the outlet of the capillary  124  into the ionisation chamber  310 . This enhances or enables the spraying of the eluent from the capillary  124  into the ion source  300 . A voltage on the capillary  124  at the liquid outlet transfers voltage from the capillary  124  to the eluent as it enters the ionisation chamber  310  causing ionisation to occur. 
         [0203]    The high voltage may be applied to the tube member  210  internally within the adaptor or spectrometer and passed from the tube member  210  to the probe assembly  110  via the ferrule  128 . 
         [0204]    In other embodiments, e.g. where the ionisation source is an APCI ion source, as shown in  FIG. 8 , the tube member  210  of the adaptor  200  may comprise an internal nebuliser gas tube  211  that, when the probe assembly  110  is inserted into the adaptor  200  (via the orifice), surrounds the capillary  124 , the member  126 , the capillary joint  134  between the capillary  124  and the liquid line  118 , and part of the liquid line  118 . 
         [0205]    In use, eluent received from the liquid chromatography device passes from the liquid inlet  116  of the probe assembly, through the liquid line  118 , the capillary joint  134 , through the capillary  124 , to the liquid outlet  144 , into the probe tip region  220 , and then into the ionisation chamber  310  of the spectrometer. A nebuliser gas flow is arranged to flow along the nebuliser gas tube  211  of the tube member  210  towards the outlet of the capillary  124 . The gas flow will flow past the outlet of the capillary  124  into the probe tip region  210 . This enhances or enables the spraying of the eluent from the capillary  124  into the probe tip region  210 . A heater may be provided in the probe tip region  210 . 
         [0206]      FIG. 9  show a view of the probe tip  220  of the probe adaptor assembly  200 . The probe tip  220  is releasably attachable to the outlet end of the tube member  210  of the adaptor  200 . The probe tip  220  may be attached to the outlet end of the tube portion  210  by any suitable and desired means, such as by one or more screws, a screw fitting, a clamp, or a bayonet, optionally together with a washer or gasket  224 . 
         [0207]    The probe tip includes a nebuliser gas capillary  221  that extends though the main body of the probe tip  220 . In some (ESI) embodiments, the downstream end of the nebuliser gas capillary  221  may protrude from the downstream end of the probe tip  220 . In other (APCI) embodiments, the downstream end of the nebuliser gas capillary  221  is enclosed within the probe tip  220   
         [0208]    When the probe tip  220  is attached to the tube member  210  of the adaptor  200 , the upstream end of the nebuliser gas capillary  221  will extend into the downstream end of the nebuliser gas tube  211 , and will be arranged to be in fluid communication with the downstream end of the nebuliser gas tube  211 . The nebuliser gas capillary  221  may be substantially coaxially arranged with respect to the nebuliser gas tube  211 . 
         [0209]    When the probe assembly  110  is installed in the adaptor  200 , the capillary  124  of the probe assembly is positioned within the nebuliser capillary  221 , i.e. coaxially within the nebuliser capillary  221 . A portion of the capillary  124  may extend beyond the nebuliser gas capillary  221 , i.e. such that when the adaptor  200  is installed into the ion source  300 , the downstream (outlet) end of the capillary  124  may extend into the ionisation chamber  310  (e.g. for ESI) or into the probe tip region  220  (e.g. for APCI). 
         [0210]    In use, the nebuliser gas flow that flows along the nebuliser gas tube  211  is arranged to flow from the nebuliser gas tube  211  through the nebuliser gas capillary  221  and into the ionisation chamber  310  or into the probe tip region  220 . As described above, the gas flow will flow past the outlet of the capillary  124  into the ionisation chamber  310  or into the probe tip region  220 , to thereby enhance or enable the spraying of the eluent from the capillary  124  into the ion source  300  or into the probe tip region  220 . 
         [0211]    When installing the probe assembly  110  into the adaptor  200 , the capillary  124  of the probe assembly must be passed through the nebuliser gas capillary  221 . 
         [0212]    As illustrated by  FIGS. 10A and 10B , this can be relatively difficult since the cross sectional area of the upstream entrance to the nebuliser gas capillary is relatively small, e.g. when compared with the total cross-sectional area of the nebuliser gas tube. This is particularly difficult when the probe assembly can only be handled from the opposite (inlet) end of the probe assembly. 
         [0213]    Accordingly, the probe tip must typically be removed in order to install the probe assembly into the spectrometer. This allows the outlet end of the probe assembly (the outlet end of the capillary) to be handled and/or the probe tip itself to be handled so that the capillary can be threaded through the nebuliser gas capillary. Removing the probe tip typically requires tools, and can accordingly be an awkward and time-consuming task. It may also be necessary to open the ionisation chamber of the ion source, i.e. to the ambient atmosphere, in order to access and remove the probe tip, which can again add time and complexity to the task of installing the probe assembly. 
         [0214]    As shown in  FIG. 11 , according to various embodiments, the probe tip  220  comprises an internal guiding member  222  that is configured to allow the capillary  124  of the probe assembly to be located within the nebuliser gas capillary  221 . The guiding member  222  may comprise, for example, a funnel  223  arranged at and in fluid communication with the upstream entrance to the nebuliser gas capillary  221 . The funnel  223  may be arranged so as to be coaxially aligned with the nebuliser gas capillary  221 , with the narrow end of the funnel  223  substantially adjacent to or in close proximity with the upstream entrance to the nebuliser gas capillary  221 . 
         [0215]    In this case, as the probe assembly  110  is inserted in to the adaptor  200 , the capillary  124  of the probe assembly  110  will pass through the main body  230  of the adaptor, through the nebuliser gas tube  211  and towards the funnel  223  of the guiding member  222 . When the outlet (downstream) end of the capillary  124  reaches the funnel  223  and as the probe assembly  110  is inserted deeper into the adaptor  200 , the funnel  223  will act to guide the capillary  124  into and then through the nebuliser gas capillary  221 . 
         [0216]    Accordingly, the provision of a guiding member  222  in accordance with various embodiments removes the need for a user to accurately align the capillary  124  with the nebuliser gas capillary  221  when installing the probe assembly  110  in the adaptor or spectrometer. That is, the capillary  124  can be inserted into the nebuliser gas capillary  221  when handling the probe only from the opposite (inlet) end of the probe assembly. This in turn beneficially removes the need to remove the probe tip  220  when installing the probe assembly in the adaptor  200  or spectrometer. Equally, the adaptor need not be removed and/or the ion source need not be opened in order to install a probe assembly  110  in the adaptor or spectrometer. 
         [0217]    Accordingly, the provision of a guiding member  222  according to various embodiments beneficially reduces the time required to install the probe assembly  110 , and can facilitate tool-free installation of the probe assembly  110  in the adaptor  200  or spectrometer. 
         [0218]    Nevertheless, as described above the probe tip  220  may be removed from the tube member  210  of the probe adaptor  200 , e.g. for cleaning, maintenance, replacement, etc. Although this may require tools, the provision of the guiding member  222  means that the probe tip  220  need not be removed in order to install or remove the probe assembly  110 . 
         [0219]      FIGS. 12A and 12B  show detailed views of the main body  230  and the cap  240  of the probe adaptor  200 . The cap  240  is removably attachable to the main body  230  of the probe adaptor. 
         [0220]    The adaptor  200  according to various embodiments may be configured such that any suitable type of atmospheric pressure ionisation ion source may be coupled to the mass and/or ion mobility spectrometer. In particular, as shown in  FIG. 12A , the adaptor  200  may comprise an electrospray ionisation (“ESI”) probe adaptor, and as shown in  FIG. 12B , the adaptor may comprise an atmospheric pressure chemical ionisation (“APCI”) probe adaptor. As will be appreciated, the provision of multiple types of adaptor means that the type of ionisation source that is coupled to the spectrometer can be changed in a relatively simple and convenient manner, i.e. by changing the adaptor. 
         [0221]    As illustrated in  FIGS. 12A and 12B , the caps  240  for the plural types of adaptor are substantially identical. Accordingly, the cap  240  may be universal for multiple types of adaptor. 
         [0222]    As described above, the adaptor  200  is configured such that the outlet end  120  of the probe assembly can be inserted into the adaptor  200  via an orifice, and can be releasably secured in the adaptor, e.g. by screwing the outlet attachment fitting  122  into a screw threaded portion of an adaptor screw fitting  231 . As shown in  FIG. 13 , a portion of the adaptor fitting  231  may extend beyond (may sit proud of) the main body  230  of the adaptor. 
         [0223]    The adaptor  200  may be configured such that when the adaptor  200  supplies a voltage to the capillary  124  via the ferrule  127 , the adaptor fitting  231  may receive a voltage. For example, the fitting  231  may form part of or may be in electrical contact with the tube member  210  and/or the the nebuliser gas tube  211  to which the voltage is applied (and from which the voltage is passed to the probe assembly  110  via the ferrule  128 ). In this case, there is a risk of electrical shock if a user is able to access the fitting  231  when a voltage is being supplied to the capillary  124 . 
         [0224]    It would be possible to electrically isolate (at least) the portion of the fitting  231  that extends beyond the adaptor main body  230  to attempt to address this problem. In some embodiments, a voltage is not supplied to the capillary  124 . However, liquid, e.g. due to a leak, within the fitting  231  or otherwise may form an electrical connection between one or more of the internal electrically conductive parts of the adaptor  200  (e.g. with ferrule  127  or the part of the adaptor  200  that provides the voltage to the ferrule  127  or otherwise) and the outside of the adaptor main body  230 , e.g. in the vicinity of the fitting  231 . The presence of liquid in the vicinity of the adaptor fitting  231  may be relatively common, for example due an eluent leak within the attachment device  122  or otherwise, e.g. due to a user incorrectly attaching the attachment device  122  of the probe assembly  110  to the adaptor  200 . 
         [0225]    Accordingly, there is in general a risk of electrical shock if a user is able to access the fitting  231  or its vicinity when a voltage is being supplied to the capillary  124 . 
         [0226]    Furthermore, contact with leaked eluent (which may comprise solvent) can also be hazardous to a user, even if the user wears gloves (e.g. if the solvent is able to pass through the gloves). In addition, the presence of solvent in the vicinity of the electrical components of the adaptor can be a fire hazard. 
         [0227]    Accordingly, a cap  240  is provided, where the cap covers (encloses) the fitting  231  and its vicinity when the cap  240  is secured to the main body  230  of the adaptor  200 . The cap  240  is configured such that a user cannot access the fitting  231  and its vicinity when the cap  240  is secured to the adaptor main body  230 . In particular, the cap  240  is configured such that a user cannot introduce objects, such as a probe assembly  110 , to the fitting  231  and its vicinity when the cap  240  is secured to the adaptor main body  230 . 
         [0228]    The adaptor  200  may further comprise a device configured to detect when the cap  240  is properly secured to the adaptor main body  230 . The device may comprise, for example, a magnetic and/or voltage operated switch device. When it is detected that the cap  240  is secured to the main body  230 , i.e. so as to prevent access to the fitting  231 , then the voltage and/or an internal gas source or vacuum pump may be turned on (or the adaptor may be configured such that the voltage and/or an internal gas source or vacuum pump are able to be turned on). When it is detected that the cap  240  is not secured to the main body  230 , i.e. such that the fitting  231  is accessible, then the voltage and/or an internal gas source or vacuum pump may be turned off (and/or the adaptor may be configured such that the voltage and/or an internal gas source or vacuum pump are unable to be turned on). This arrangement beneficially prevents a user coming into contact with the high voltage that may be applied to the capillary  124  via the adaptor  200  and/or leaked eluent, etc. 
         [0229]    As shown in  FIGS. 12A and 12B , the cap  240  is securable to the main adaptor body  230  so as to prevent access to the fitting  231  and its vicinity when a probe assembly  110  is not attached to (when the probe assembly  110  is detached from) the adaptor  200 . The cap  240  should also be securable to the adaptor main body  230  (so as to prevent access to the fitting  231  and its vicinity) when a probe assembly  110  is attached to the adaptor  200 . However, as described above, the inlet end  112  of the probe assembly  110  is, in use, attached to a (separate) chromatography device. 
         [0230]    Accordingly, as shown in  FIG. 13 , the cap  240  includes an aperture  241  through which at least a portion of the probe assembly  110  can pass. The aperture  241  may be shaped and/or sized such that the inlet end attachment fitting  114  of the probe assembly  110  can pass through the aperture  241 , e.g. such that the inlet end attachment fitting  114  of the probe assembly  110  can only just pass through the aperture  241 , i.e. so as to prevent larger objects and/or other incompatible types of probe from passing though the aperture  241 . 
         [0231]    The aperture  241  is arranged such that when the probe assembly  110  is installed in the adaptor  200 , the liquid line  118  can pass through the aperture  241 , e.g. when the cap  240  is secured to the main adaptor body  230 . The aperture  241  may be arranged such that when the cap  240  is secured to the adaptor main body  230 , then the aperture is substantially aligned with the orifice/fitting  231  in the main body  230 . The aperture  241  and the orifice/fitting  231  may or may not be coaxially aligned. For example, at least a portion of the aperture  241  may intersect with a central longitudinal axis of the orifice, where the portion of the aperture  241  that intersects with the axis may be the centre of the aperture  241 , or some other non-central part of the aperture  241 . 
         [0232]      FIG. 13  shows a detailed view of the adaptor main body  230  and the cap when a probe assembly  110  is inserted into the adaptor  200 . As shown in  FIG. 13 , when the probe assembly  110  is installed in the adaptor  200 , the attachment device  122  of the probe assembly  110  is attached to (e.g. screwed into) the fitting  231  of the adaptor main body  230 . In this configuration, (most of) the capillary  124 , the member  126 , the capillary joint  134  between the capillary  124  and the liquid line  118 , and part of the liquid line  118 , which are not visible in  FIG. 13 , will be enclosed within the adaptor main body  230  and the adaptor tube member  210 . A portion of the attachment  122  extends beyond the fitting  231  externally to the adaptor main body  230 . The portion of the line  118  upstream of the attachment device  122  extends from the attachment device  122 , through the aperture  241  in the cap  240  and onwardly to the chromatography device (not shown). 
         [0233]    The cap  240  is configured such that when the probe assembly  110  is installed in the adaptor  200 , and the cap  240  is secured in place, access to the fitting  231  and its vicinity is restricted by the cap  240 . Accordingly, the risk of electrical shock, contact with solvent, etc., is reduced. 
         [0234]    However, the provision of the aperture  241  in the cap  240  may allow access to the fitting  231  or its vicinity when the probe assembly  110  is detached from the adaptor  200 , and when the capillary voltage is being supplied to the capillary  124 , i.e. when the cap  240  is secured to the main adaptor body  230 . 
         [0235]    Accordingly, the cap  240  is provided with a device for closing the aperture  241  and/or otherwise preventing access to the fitting  231  or its vicinity via the aperture  241  when the cap  240  is secured to the adaptor main body  230  and when a probe assembly  110  is not attached to the adaptor  200  (when the probe assembly  110  is detached from the adaptor  200 ). 
         [0236]    The device may take any suitable form, but as shown in  FIGS. 14A and 14B  the device may beneficially take the form of one or more balls, e.g. a ball bearing  242 , provided internally within the cap  240 . However, the device need not be in the form of a ball, and may comprise some other object provided internally within the cap. The cap  240  may be configured such that the ball  242  or other object may freely move within an internal hollow portion of the cap  240 , but such that the ball or other object is contained within the cap  240 , i.e. cannot be removed from the hollow portion of the cap  240  in normal operation (without e.g. dismantling the cap  240 ). Accordingly, the ball bearing  242  or other object and/or aperture  241  has an appropriate size and/or shape such that the ball  242  or other object cannot pass though the aperture  241 , e.g. the diameter of the ball  242  or other object is greater than the diameter of the aperture  241 . However, the cap  240  may be configured such that the ball  242  or other object cannot fully seal the aperture  241 . 
         [0237]    As shown in  FIGS. 14A and 14B , the hollow portion of the cap  240  may comprise a first internal pocket  243  for receiving the ball  242  or other object. The first pocket  243  is configured such that the ball bearing  242  or other object cannot leave the internal hollow portion of the cap  240  via the first pocket  242 , e.g. a (minimum) internal diameter of the pocket  243  is less than the diameter of the ball  242  or other object. The cap  240  is configured such that when the cap  240  is in or is close to an upright position (i.e. when a central longitudinal axis of the cap  240  is substantially vertical, e.g. when the cap  240  is secured to the adaptor main body  230 ) (and when a probe assembly  110  is not installed in the adaptor  200 ), then the ball bearing  242  or other object will fall (under the influence of gravity) into the first pocket  243 . For example, the cap  240  may comprise a funnel portion arranged such that when the cap  240  is in or is close to an upright (vertical) position the ball  242  or other object will fall within the funnel portion under the influence of gravity into the first pocket  243 . 
         [0238]    The cap  240  is configured such that when the ball bearing  242  or other object is positioned within the first pocket  243  (and when the cap  240  is secured to the adaptor main body  230 ), then the ball bearing  242  or other object prevents access to the screw fitting  231  or its vicinity via the aperture  241 . 
         [0239]    As will be appreciated, this arrangement prevents the probe  110  assembly from coming into contact with the fitting  231  or its vicinity, e.g. if an inexperienced user attempts to insert the probe assembly  110  into the adaptor  200  when the cap  240  is closed (and therefore when a voltage is potentially being applied to the capillary  124 ). This also prevents other objects (e.g. fingers, tools, etc.) from coming into contact with the fitting  231  or its vicinity when the cap  240  is closed. The risk of electrical shock or contact with solvent to the user is therefore substantially reduced. 
         [0240]    The cap  240  may be configured such that the ball  242  or other object cannot fully seal the aperture beneath the first internal pocket  243 . As shown in  FIG. 15 , when the ionisation region  310  of the ion source and/or tube portion  210  is pressurised, the ball  242  or other object may be configured to be ejected from the first internal pocket  243 . In this case, an audible hiss from gas escaping via the adaptor  200  may alert the user to the fact that a probe assembly is not installed. 
         [0241]    When installing the probe assembly  110  into the adaptor  200 , the probe assembly  110  is passed through the aperture  241  in the cap  240 . However, the ball  242  or other object may interfere with this operation. Accordingly, one or more second pockets  244  are provided in the internal hollow portion of the cap  240  for receiving the ball  242  or other object. 
         [0242]    As shown in  FIGS. 16A and 16B , the one or more second pockets  244  may be arranged such that when the cap  240  is not in or is not close to the upright (vertical) position (e.g. when the cap  240  is in or is close to a horizontal position), then the ball bearing  242  or other object will fall (under the influence of gravity) into one or the one or more second pockets  244 . For example, tilting the cap  240  sufficiently far away from the upright position may cause the ball  242  or other object to move into one of the one of more second pockets  244 . 
         [0243]    The adaptor  200  is generally arranged such that it is necessary to remove the cap  240  from the main adaptor body  230  in order to rotate the cap  240  sufficiently far away from the upright position to cause the ball  242  or other object to move into one of the one of more second pockets  244 . Accordingly, the aperture  241  is openable only when the adaptor  200  is not supplying the voltage to the capillary  124 . 
         [0244]    The cap  240  should be configured such that when the cap  240  is rotated by 90 degrees relative to the upright (vertical) position (about a rotation axis orthogonal to the central longitudinal axis of the cap  240 ) then the ball bearing  242  or other object will fall into one of the one or more second pockets, but the cap  240  may also be configured such that the ball bearing  242  or other object will fall into one of the one or more second pockets when the cap  240  is rotated by less than 90 degrees relative to the upright (vertical position). The angle or angles relative to the upright (vertical) position at which the cap  240  must be held in order for the ball bearing or other object to fall into one of the one or more second pockets  244  may be selected as desired. 
         [0245]    As shown in  FIG. 16B , the cap  240  is configured such that when the ball bearing  242  or other object is positioned within one of the one or more second pockets  244  then the aperture  241  is opened, i.e. so that the probe assembly  110  can be passed through the aperture  241 , e.g. without the ball  242  or other object interfering with this operation. 
         [0246]    The one or more second pockets may comprise a single pocket, e.g., that extends in a loop around the aperture  241  (as shown in  FIGS. 16A and 16B ), or may alternatively comprise any suitable plural number of discrete pockets. 
         [0247]    As shown in  FIGS. 13 and 17 , the cap  240  is configured such that when the ball bearing  242  or other object is positioned within the one or more second pockets  244 , and when the cap  240  is returned to or close to its upright position (e.g. when the cap  240  is secured to the main adaptor body  230 ), then the ball bearing  242  or other object will fall into the first pocket  243  when no probe assembly  110  is installed in the adaptor (when the probe assembly  110  is detached from the adaptor  200 ), or will not move into the first pocket  243 , e.g. will substantially remain within the second pocket  244 , when a probe assembly  110  is installed in the adaptor  200 . For example, when the probe assembly  110  is inserted through the aperture  241 , the line  118  of the probe assembly  110  may cause the ball bearing  242  or other object to remain within the second pocket  244 . 
         [0248]    It will accordingly be appreciated that the cap  240  is provided with a device for closing the aperture  241  and/or otherwise preventing access to the fitting  231  or its vicinity via the aperture  241  when the cap  240  is secured to the adaptor main body  230  and when a probe assembly  110  is not attached to the adaptor  200  (when the probe assembly  110  is detached from the adaptor  200 ). The device is configured such that when the aperture  241  is closed, the aperture  241  may be opened only when the cap  240  is removed from the adaptor main body  230  (i.e. when the cap  240  is opened). The device is, however, configured to remain open when a probe assembly  110  is installed in the adaptor  200  and the cap  240  is secured to the main adaptor body  230  (i.e. when the cap  240  is closed). The risk of electrical shock and/or contact with solvent, etc., to the user is therefore substantially reduced. 
         [0249]    As described above, in some (e.g. ESI) embodiments, when the probe assembly  110  is installed in the adaptor  200 , a portion of the outlet (downstream) end of the capillary  124  will extend beyond (downstream of) the probe tip  220 , i.e. beyond (downstream of) the nebuliser gas capillary  221 . 
         [0250]    As illustrated in  FIG. 18 , in other (e.g. APCI) embodiments, when the probe assembly  110  is installed in the adaptor  200 , a portion of the outlet (downstream) end of the capillary  124  will extend beyond (downstream of) the nebuliser gas capillary  221 , but within the probe tip  220 . 
         [0251]    The position of the capillary  124  relative to the nebuliser gas capillary  221  is an important parameter that must be tightly controlled in order to optimise the ionisation process and/or in order to maintain a consistent ionisation process. For example, changes in the position of the outlet end of the capillary relative to the outlet end of the nebuliser gas capillary  221  can cause undesirable variations in the ionisation process. 
         [0252]    As discussed above, in conventional arrangements, in order to remove the probe assembly  110  from the spectrometer, it is necessary to disassemble the probe tip  220 . This necessarily means that the position of the outlet end of the capillary  124  relative to the outlet end of the nebuliser gas capillary  221  is lost. Thus, in conventional arrangements when a probe assembly  110  is removed and subsequently replaced, or when another probe assembly is installed in the spectrometer, the position of the outlet end of the capillary  124  relative to the outlet end of the nebuliser gas capillary  221  changes. The position must then be re-optimised or re-adjusted, thereby increasing downtime and cost for the spectrometer. 
         [0253]    The adaptor  200  according to various embodiments described herein is provided with an adjustment mechanism that facilitates tool-free adjustment of the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221 . This means that the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  can be relatively easily and conveniently adjusted and/or optimised. 
         [0254]    Furthermore, the adjustment mechanism according to various embodiments is configured such that when a probe assembly  110  is removed and subsequently replaced from the adaptor  200 , or when another probe assembly  110  is installed in the adaptor  200 , the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  substantially does not change, i.e. remains substantially fixed, or changes by a relatively small amount. This can reduce the amount of re-optimising or re-adjusting required, and may mean that the position does not need to be re-optimised or re-adjusted, thereby reducing downtime and cost associated with the spectrometer. 
         [0255]    According to various embodiments, the adaptor  200  is provided with an adjustment mechanism or other control device for adjusting the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221 . As shown in  FIG. 13  (and elsewhere), the adjustment mechanism may comprise a rotating dial  246  that is e.g. positioned on an external surface of the cap  240 . This facilitates real-time optimising or adjustment of the distance, or “live tuning”, e.g. during an experiment. 
         [0256]    Rotation of the dial may cause the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  to change. The adaptor  200  may comprise any suitable mechanism in order to facilitate this, such as one or more cams, one or more lifting cams, and the like. 
         [0257]      FIG. 19  shows a cut away detailed view of the cap  240  and the main adaptor body  230  in accordance with an embodiment. The rotating dial  246  may be connected to a first mechanism in the cap  240  that is configured to engage with a corresponding second mechanism in the adaptor main body  230 , i.e. such that rotation of the dial  246  causes the second mechanism in the adaptor main body  230  to rotate (via rotation of the first mechanism in the cap  240 ) (when the cap  240  is secured to the main adaptor body  230 ). 
         [0258]    For example, as shown in  FIG. 19 , the first mechanism may comprise a first set of teeth  247 , and the second mechanism may comprise a corresponding second set of teeth  232 . Each set of teeth may comprise plural teeth, e.g. having a circular arrangement that may be arranged to be coaxially aligned with the central longitudinal axis of the adaptor  200 . In use, the first  247  and second  232  sets of teeth may face one another and may be configured so as to engage when the cap  240  is secured to the main adaptor body  230  (i.e. when the cap  240  is closed). Rotation of the dial  246  may cause the first set of teeth  247  to rotate, which in turn may cause the second set of teeth  232  to rotate (when the teeth are engaged, i.e. when the cap  240  is closed). Rotation of the second set of teeth  232  may cause the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  to be adjusted, e.g. via an appropriate mechanism (comprising one or more cams, one or more lifting cams, and the like) in the main adaptor body  230 . 
         [0259]    The dial  246  and/or the first set of teeth  247  may be continuously rotatable, i.e. the dial  246  and/or the first set of teeth  247  may have no preferred or “home” rotational position. 
         [0260]    As such, rotation of the dial  246  may cause the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  to be adjusted. The dial  246  may be rotated without tools, and so this adjustment mechanism facilitates tool-free adjustment of the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221 . 
         [0261]    Furthermore, the provision of plural engaging teeth in accordance with various embodiments means that when the teeth of the first  247  and second  232  sets of teeth are not aligned as the cap  240  is secured to the main adaptor body  230  (as the cap  240  is closed), then the rotational position of the second set of teeth  232  can only ever be altered by a maximum of half the pitch of the teeth when the cap  240  is secured to the main adaptor body  230 , and so the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  will only ever be altered by a correspondingly small amount (that e.g. depends on the pitch of the teeth, and the pitch of the one or more cams or other devices to which the teeth are connected, and which may be selected as desired). 
         [0262]    According to various further embodiments, one or both of the first  247  and second  232  sets of teeth may be spring loaded. That is, one or more springs or other elastic devices may be provided that are connected to the first  247  and/or second  232  sets of teeth. In this case, the first  247  and/or second  232  sets of teeth may be configured to be moveable, e.g. in the direction parallel to the central longitudinal axis of the orifice. The one or more springs or other elastic devices may be configured so as to be elastically deformed when the first  247  and/or second  232  sets of teeth are moved in this manner. This arrangement prevents the rotational position of the second set of teeth  232  from being altered (and therefore prevents the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  from being altered (at all)) when the first  247  and/or second  232  sets of teeth are brought into the engaged position when the teeth are not aligned. 
         [0263]    In this case, rather than altering the rotational position of the second set of teeth  232  when the teeth are not aligned as the teeth are engaged, the longitudinal direction of the first  247  and/or second  232  set of teeth is instead altered, as the one or more springs or other elastic devices are deformed. Rotation of the first set of teeth  247  (due to rotation of the dial  246 ) will cause the teeth to become fully engaged as the two sets of teeth become properly aligned (and as the one or more springs or other elastic devices cause the first and/or second set of teeth to become fully engaged), without the rotational position of the second set of teeth  232  being altered. 
         [0264]    This beneficially means that the teeth can be engaged with one another as the cap  240  is closed substantially without affecting the rotational position of the second set of teeth  232 . This in turn means that when the cap  240  is opened and/or when a probe assembly  110  is removed from the adaptor  200  and is subsequently replaced, or when another probe assembly  110  is installed in the adaptor  200 , the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  substantially does not change, i.e. remains substantially fixed. 
         [0265]    This arrangement also facilitates real-time optimising or adjustment of the distance during an experiment, e.g., “live tuning”. 
         [0266]    Where the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  reaches a minimum or maximum, the provision of a spring loaded mechanism will also allow the first and/or second sets of teeth to then disengage, e.g. such that rotation of the dial  246  causes rotation of the first set of teeth  247 , but not of the second set of teeth  132 , i.e. as the first set of teeth  247  “ride” over the second set of teeth  132 . An audible “clicking” sound when this occurs will alert a user to the fact that the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  has reached its minimum or maximum value. The surfaces of the teeth may be arranged to be resistant to wear. 
         [0267]      FIGS. 20A, 20B, 20C, 21A, 21B, 22A and 22B  illustrate the mechanism in more detail in accordance with an embodiment. 
         [0268]    In this case, when the cap  240  is fitted to the main adaptor body  230 , the two sets of teeth will turn together. As the teeth rotate, a cam slides along a dowel. The fitting  231  may be fixed (i.e. unable to rotate).  FIGS. 20A, 20B and 20C  illustrate the mechanism when it is in its lowest position (i.e. where the capillary  124  protrusion is greatest). 
         [0269]    As the cam rotates, the gap from the bearing face of the dowel to the cam increases. This may be due to gas pressure from the ion source  310 . The fitting  231  is pushed up (in the direction shown by the arrow in  FIGS. 21A and 21B  thereby increasing the distance “X”. This decreases the capillary protrusion, i.e. because the probe, which has a fixed length, is fitted to the fitting  231 . 
         [0270]    According to various embodiments, the probe capillary does not rotate, but rather just moves in the axial “Z” direction, e.g. to a maximum “X+”, e.g. up until the stop of the cam. 
         [0271]    In some embodiments, one or two or more dowels may be provided and used, e.g. such that one is always in the slot. 
         [0272]      FIG. 23A  shows the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  in a relatively extended position.  FIG. 23B  shows the position of the outlet (downstream) end of the capillary  124  relative to the outlet (downstream) end of the nebuliser gas capillary  221  in a relatively retracted position. 
         [0273]      FIGS. 24A, 24B, and 24C  show detailed views of the adaptor main body  230  and the cap  240  when a probe assembly  110  is installed in the adaptor  200  and when the cap  240  is closed, i.e. when the cap  240  is secured to the main adaptor body  230 . 
         [0274]    In use, the inlet end  112  of the probe assembly is attached to a chromatography device (not shown) (as described above). 
         [0275]    The attachment device  114  at the inlet end  112  of the probe may be able to slide along the liquid line  118  and may be able to rotate about the liquid line  118 . This allows the user to push the tube well into the supply fitting of the liquid chromatography device so as to reduce the dead volume. The attachment device  114  may then be rotated so as to screw it into the liquid chromatography device outlet and so as to make a seal therewith. Beneficially, this removes any need to twist the liquid line  118 , which would otherwise stress the tube. 
         [0276]    However, since the attachment relies on a user forming the attachment correctly, it is possible that a leak may develop between the chromatography device and the attachment device  114 . In this case, it is possible that liquid may track along the liquid line  118  towards the adaptor  200 . As discussed above, the presence of liquid gives rise to the risk of electrical shock and other risks to the user and/or to the instrument such as combustion of solvent, contact of liquid with electrical systems, and the user contacting solvent, etc. In addition, other liquid may be accidentally spilled on the adaptor, or otherwise (unintentionally) introduced to the adaptor. 
         [0277]    In order to further address these problems, the adaptor main body  230  and/or cap  240  is configured such that liquid incident upon the adaptor main body  230  and/or the cap  240  will be directed away from the adaptor and/or probe interior. The adaptor main body  230  is provided with a liquid gutter or gully  233  which is arranged to collect liquid incident upon the adaptor main body  230  and/or the cap  240  and direct that fluid to a liquid drain or spout  234 . 
         [0278]    As shown in  FIGS. 25A, 25B, and 25C , the gutter  233  is formed substantially continuously around the adaptor main body  230 , e.g. 360 degrees around the sides of the adaptor  200 , i.e. such that liquid incident upon most or all of the adaptor main body  230  and/or the cap  240  is collected by the gutter  233 . The gutter  233  is configured such that collected liquid is directed to the liquid drain or spout  234 , e.g. due to a sloping gutter floor. 
         [0279]    The gutter  233  may be open-topped or otherwise arranged such that a user will be alerted to the presence of liquid in the gutter  233 , e.g. by visual inspection, and thereby to the presence of a leak in the system. 
         [0280]    The gutter  233  and/or drain  243  may be arranged so as to be fixed to the adaptor main body, e.g. such that the gutter  233  and/or drain  243  cannot be removed, e.g. when a user installs a probe into the adaptor  200 . 
         [0281]    The drain  234  is arranged such that the liquid collected by the gutter  233  will drip or otherwise fall from the drain  234 . By arranging for the liquid to drip in this way, a continuous electrical conduction path cannot be formed by the unwanted liquid, thereby reducing the risk of electrical shock. 
         [0282]    The drain  234  may be arranged such that the drain maintains a fixed position, e.g. relative to the adaptor  200 . Accordingly, liquid collected by the gutter  233  will drip or otherwise fall in a position selected by a user. 
         [0283]    According to various embodiments, the drain  234  comprises one or more (open-ended) slots or other indentations. In use, the liquid drips via the one or more slots or other indentations. This is beneficial, e.g. when compared to a drain comprising an aperture or hole, since the provision of one or more open ended slots or other indentations means that there is no possibility of the drain becoming blocked, e.g. due to high viscosity liquid, distilled components, etc. blocking the aperture or hole. 
         [0284]    As shown in  FIG. 25C , a portion of the gutter  233  that is in proximity with the drain  234  may comprise a relatively wide channel region that is configured to direct liquid collected in the gutter  233  to the liquid drain  234 , e.g. due to a sloping floor. According to various embodiments, the channel region may be provided with a fin, bump, ridge or other protrusion  235 . 
         [0285]    As illustrated by  FIGS. 26A and 26B , the fin, bump, ridge or other protrusion  235  is arranged so as to reduce the possibility of the channel region and/or drain  234  becoming blocked, e.g. by a foreign object  400  being placed in the channel region and/or drain  234  region. In particular, the fin, bump, ridge or other protrusion  235  may be arranged such that a flat surface seal cannot or is less likely to form between a foreign object  400  and the channel region and/or drain  234  region. In particular, the fin or other protrusion  235  may be arranged such that the channel region and/or drain  234  cannot be blocked by the inlet end  112  of the probe assembly  110 , a cap or other fitting. 
         [0286]    According to various embodiments, the adaptor main body  230  is also provided with a device  236  for holding the inlet end  112  of the probe assembly  110 , i.e. when not in use, e.g. a “parking space” for the inlet end  112  of the probe assembly  110 . This beneficially encourages the user to avoid using the gutter  233  to hold the inlet end  112  of the probe assembly, which may cause blockages. 
         [0287]    According to various embodiments, the cap may be attached to the main body  230 , e.g. by a cord, hinge, or other means. For example, as shown in  FIGS. 27A and 27B , the cap  240  may be attached to the adaptor main body  230  by a cord or lanyard  248 . This beneficially prevents the cap from being lost. This also simplifies the process of removing/installing a probe assembly in the adaptor  200  since, for example, it is not necessary for a user to keep hold of the cap  240 . 
         [0288]    According to an embodiment, the cap  240  and/or main adaptor body  230  comprises one or more asymmetric mating portions, e.g. such that the cap  240  can be secured to the main adaptor body  230  (i.e. can be closed) only in one (correct) orientation and/or position. 
         [0289]    According to an embodiment, the cap  240  and/or main adaptor body  230  is configured so as to produce one or more audible clicks when the cap  240  is fitted securely to the main adaptor body  230 . 
         [0290]    According to an embodiment, the cap  240  is configured such that tools are not required in order to open the cap  240  (to remove the cap  240  from the main adaptor body  230 ). The cap  240  may comprise one or more buttons, configured such that when the button(s) are pushed, the cap  240  is opened. 
         [0291]    In particular, the cap  240  may comprise two buttons or flippers, configured such that when the buttons are pushed together, the cap  240  is opened. The two buttons or flippers may be arranged such that a user must deliberately intend to open the cap  240  in order for the cap to be opened. For example, the two buttons may be configured such that a pinching action is required in order to open the cap  240 . It would also be possible to provide more buttons or flippers, e.g. three or more, that must simultaneously be operated or otherwise to open the cap  240 . 
         [0292]    The one or more buttons may be configured such that the cap can be opened and removed in one motion. The cap may be configured such that the cap may be opened whether a probe assembly is installed or not. 
         [0293]    The cap  240  may be provided with one or more springs or other elastic devices configured such that when the cap  240  is opened, the cap  240  is ejected from the main adaptor body  230 . 
         [0294]    Although various embodiments have been described for use in an electrospray ion source, it may be used in other types of ion source such as an atmospheric pressure chemical ionisation source (APCI) or an impactor spray ion source. 
         [0295]    Although the above embodiments have been described primarily in terms of a probe adaptor assembly, it would also or instead be possible for one or more of all of the components of the adaptor to be integrated with the ion source and/or the spectrometer. 
         [0296]    Although the present invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.