Axial atmospheric pressure photo-ionization imaging source and inlet device

Abstract

An ambient or atmospheric pressure ion source is disclosed that comprises a laser source (1) that generates ions and/or neutral particles from a target (2). A transfer device (10) causes the ions and/or neutral particles to pass along a first path or axis within the transfer device (10), while a secondary activation device (6) directs laser radiation or photons along, across or over at least a portion of the first path or axis to cause secondary activation of the ions and/or neutral particles.

Claims

1. An ambient or atmospheric pressure ion source comprising: a first laser source arranged and adapted to generate ions and/or neutral particles from a target; a transfer device arranged and adapted to cause said ions and/or said neutral particles to pass along a first path or axis within said transfer device, wherein said transfer device comprises a housing having an inlet through which said ions and/or said neutral particles enter said transfer device and an outlet through which said ions and/or further ions and/or neutral particles may exit said transfer device; and a secondary activation device which is arranged and adapted to direct laser radiation or photons along, across or over at least a portion of said first path or axis so as to cause secondary activation of said ions and/or said neutral particles.

2. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said transfer device comprises one or more capillaries, one or more heated capillaries, one or more tubular or hollow guides or one or more tubular or hollow optical fibres.

3. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said transfer device is selected from the group consisting of: (i) a drift tube; (ii) an ion mobility separator or spectrometer; (iii) a differential ion mobility separator or spectrometer or a Field Asymmetric Ion Mobility Spectrometry (“FAIMS”) device; or (iv) a device for temporally separating ions and/or neutral particles according to a physico-chemical property.

4. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said housing comprises one or more optically transparent sections through which said laser radiation or photons pass.

5. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said transfer device further comprises one or more further inlets for introducing one or more reagents into said transfer device so that ions and/or neutral particles may be subjected to one or more reactions within said transfer device.

6. An ambient or atmospheric pressure ion source as claimed in claim 1, further comprising one or more detectors for detecting laser radiation or photons emitted from said secondary activation device before and/or during and/or after ions and/or neutral particles have been subjected to secondary activation within said transfer device.

7. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said secondary activation device comprises a laser source.

8. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said secondary activation device comprises a non-laser source of photons, one or more vacuum ultraviolet (“VUV”) lamps, one or more light emitting diodes (“LEDs”), one or more visible photon sources or one or more infra-red (“IR) photon sources.

9. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said secondary activation comprises a process involving ionisation, secondary ionisation, further ionisation, photo-ionisation or post-ionisation of said ions and/or said neutral particles.

10. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said secondary activation device comprises an ionisation device, a secondary ionisation device, a further ionisation device, a photo-ionisation device or a post-ionisation device for ionising said ions and/or said neutral particles.

11. An ambient or atmospheric pressure ion source as claimed in claim 1, wherein said secondary activation comprises a process involving photofragmentation, photo-activation, photo-dissociation, fragmentation, activation, dissociation, Electron Capture Dissociation (“ECD”), Electron Transfer Dissociation (“ETD”), declustering, reacting, fast photochemical oxidation of proteins (“FPOP”) reactions or hydrogen/deuterium exchange (“HDX”) reactions of said ions and/or said neutral particles.

12. An analytical device comprising an ambient or atmospheric pressure ion source as claimed in claim 1.

13. An analytical device as claimed in claim 12, wherein said analytical device comprises an ion mobility spectrometer or separator, a differential ion mobility spectrometer or separator or a mass spectrometer.

14. An analytical device as claimed in claim 12, wherein said analytical device further comprises an atmospheric pressure interface and wherein said transfer device is arranged and adapted to direct ions/or neutral particles towards said atmospheric pressure interface.

15. A method of generating ions at ambient or atmospheric pressure comprising: directing emission from a first laser source at a target in order to generate ions and/or neutral particles; transmitting said ions and/or neutral particles along a first path or axis within a transfer device, wherein said transfer device comprises a housing having an inlet through which said ions and/or said neutral particles enter said transfer device and an outlet through which said ions and/or further ions and/or neutral particles may exit said transfer device; and directing laser radiation or photons along, across or over at least a portion of said first path or axis so as to cause secondary activation of said ions and/or said neutral particles.

16. A method of analysis comprising a method of generating ions as claimed in claim 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various embodiments will now be described, by way of example only, and with reference to the accompanying drawing in which:

(2) FIG. 1 shows an embodiment wherein a laser is directed on to a target sample so as to generate a plume of ions and neutral particles and wherein the plume of ions and neutral particles is then directed into a capillary inlet transfer device wherein a second laser beam is focused along the axis of the capillary inlet transfer device in order to ionise neutral particles within the capillary inlet transfer device.

DETAILED DESCRIPTION

(3) FIG. 1 illustrates an embodiment wherein a first or primary laser source 1 is provided upstream of a target sample. The first laser source 1 is arranged and adapted to emit a first laser beam 4 or pulse(s) of laser radiation (or to otherwise emit photons) which may then be focused by a first focusing lens 5 on to the target sample. The first laser source may comprise, for example, an ultra-violet (“UV”) laser such as a nitrogen laser e.g. having a wavelength of e.g. 337 nm.

(4) According to other embodiments the primary laser may comprise a frequency tripled (or frequency quadrupled) Nd:YAG laser having a wavelength of 355 nm (or 266 nm).

(5) The first laser or laser system 1 may comprise a tuneable wavelength laser. For example, the first laser or laser system 1 may utilise one or more optical parametric oscillators (“OPO”) thereby enabling the wavelength of the laser light output from the first laser or laser system 1 to be varied or otherwise altered.

(6) Further embodiments are contemplated wherein laser light from the first laser source 1 may be directed on to the target sample using a fibre optic laser delivery system. The fibre optic laser delivery system may comprise one or more optical fibres.

(7) Other embodiments are contemplated wherein different primary laser sources 1 may be utilised.

(8) The target sample may comprise a sample or portion of tissue 2 which may be provided on a substrate 3 such as a metallic plate. The target sample may be embedded into a crystalline MALDI matrix in a conventional manner. However, according to other alternative embodiments is not necessary for the target to be embedded in a MALDI matrix and it is contemplated, for example, that the target sample may comprise a natural or unmodified sample which is not embedded in a MALDI matrix. According to an embodiment no chemicals, reagents or other substances may have been added to the natural or unmodified sample which is to be ionised by the first laser source 1. It will be understood that the ability to be able to analyse a natural target sample without needing to add a chemical, reagent or matrix to the sample (for reasons of wanting to improve the ionisation efficiency) is particularly beneficial.

(9) It is also not essential that the target is provided on a substrate 3 or metallic plate. For example, embodiments are contemplated wherein the primary laser 1 and the beam or pulse 4 of radiation emitted from the primary laser 1 may be directed on to a target which may comprise ex vivo or in vivo tissue and wherein the tissue is not provided on a substrate 3.

(10) Yet further embodiments are contemplated wherein the sample may involve liquid atmospheric pressure Matrix Assisted Laser Desorption Ionisation (“AP-MALDI”) or liquid extraction surface analysis (“LESA”).

(11) Liquid UV-MALDI matrices are known and provide an alternative to embedding samples to be ionised by MALDI in a crystalline matrix. The liquid matrix may comprise an ionic liquid matrix (“ILM”) which may comprise a viscous liquid matrix which may be doped with UV light absorbing chromophores. Known ionic liquid matrices which may be used in liquid MALDI techniques include equimolar mixtures of conventional MALDI matrix compounds such as 2,5-dihydroxybenzoic acid (“DHB”), α-cyano-4-hydroxycinnamic acid (“CCA”) or sinapinic acid (“SA”) together with an organic base such as pyridine (“Py”), tributylamine (“TBA”) or N,N-dimethylethylenediamine (“DMED”).

(12) Liquid extraction surface analysis mass spectrometry (“LESA-MS”) is a surface profiling technique that combines micro-liquid extraction from a solid surface with nano-electrospray mass spectrometry. One potential application is the examination of the distribution of drugs and their metabolites by analysing ex vivo tissue sections. According to an embodiment an extraction solvent may be pipetted into a robotic tip and the solvent may then be dispensed from the robotic tip onto the surface of the target sample. The target sample may comprise ex vivo tissue. Analytes are then extracted from the target sample into the solvent and the solution extract is then withdrawn or aspirated into the robotic tip. The robotic tip may then be translated so as to engage with the rear surface of, for example, an Electrospray Ionisation (“ESI”) chip. A high voltage may be applied to the pipette tip and nanoelectrospray ionisation may then be initiated. A mixture of analyte ions and neutral particles may then be released.

(13) Accordingly, embodiments are contemplated wherein the first or primary laser source 1 may be substituted with an Electrospray or nanoelectrospray ionisation device and in particular a miniature electrospray device or chip.

(14) Embodiments are also contemplated wherein Atmospheric Pressure Matrix Assisted Laser Desorption Ionisation (“AP-MALDI”) may be performed from a LESA droplet.

(15) One or more contrast reagents may be added to the sample. The one or more contrast agents may be added to the sample in order to improve optical visualisation or analysis of the sample. The one or more contrast reagents may also be added to the sample in order to improve analysis and/or imaging of the sample by e.g. Magnetic Resonance Imaging (“MRI”), MALDI mass spectrometry imaging or other imaging techniques.

(16) The one or more contrast reagents enable combined imaging techniques to be performed. The semi-quantitative nature of the image obtained according to various embodiments can be combined with e.g. a MRI image in order to improve the overall analysis quality. It will be understood that MRI quantitation can be limited.

(17) A second or secondary laser source 6 may be provided which may be arranged to emit a second laser beam or single or multiple pulses 7 of laser radiation (or to otherwise emit photons) which may then be focused by a second focusing lens 8 on to and through a first window or port 9 of an inlet transfer device or inlet transfer reaction device 10. The first window or port 9 of the inlet transfer device or inlet transfer reaction device 10 may be proximal to the second laser source 6 or other secondary activation device. The inlet transfer device or inlet transfer reaction device 10 may comprise a second window or port 11 at the other end of the inlet transfer device or inlet transfer reaction device 10 to that of the first window or port 9.

(18) A detector 18 may be provided adjacent to or in close proximity with the second window or port 11. The detector 18 may comprise a spectroscopy detector which may be arranged to detect light emitted from the second laser 6 and to detect the effect, effectiveness or progress of secondary activation of ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10. For example, the detector 18 may be used to determine the absorption spectra of material, particles or ions within the inlet transfer device or inlet transfer reaction device 10 before and/or during and/or subsequent to secondary activation or photoactivation by the secondary laser source 6 or other secondary activation device.

(19) The second laser or laser system 6 may comprise a tuneable wavelength laser. For example, the second laser or laser system 6 may utilise one or more optical parametric oscillators (“OPO”) thereby enabling the wavelength of the laser light output from the second laser or laser system 6 to be varied or otherwise altered.

(20) Further embodiments are contemplated wherein laser light from the second laser source 6 (or photons from another secondary activation device) may be directed on to and along the axis of the inlet transfer device or inlet transfer reaction device 10 using a fibre optic laser delivery system. The fibre optic laser delivery system may comprise one or more optical fibres.

(21) Other embodiments are contemplated wherein different secondary laser sources 6 may be utilised. Yet further embodiments which are discussed in more detail below are contemplated wherein the secondary laser source 6 may be replaced within a different type of secondary activation device. For example, it is not essential that the secondary activation device comprises a laser and accordingly it should be appreciated that other non-laser photo-activation devices may be utilised.

(22) As will be described in more detail below, the second laser source 6 is arranged to act as a secondary activation device with the purpose of subjecting ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10 to secondary activation. The process of secondary activation may include one or more processes such as ionisation, secondary ionisation, further ionisation, photo-ionisation or post-ionisation of ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10. The process of secondary activation may comprise photo-fragmentation, photo-activation, photo-dissociation, fragmentation, activation, dissociation, Electron Capture Dissociation (“ECD”), Electron Transfer Dissociation (“ETD”), declustering, reacting, fast photochemical oxidation of proteins (“FPOP”) reactions or hydrogen/deuterium exchange (“HDX”) reactions of ions and/or neutral particles.

(23) The inlet transfer device or inlet transfer reaction device 10 may comprise a main inlet or port 12 and optionally a first supplementary inlet or port 13 and/or optionally a second supplementary inlet or port 15. One or more reagents, chemicals, liquids or gases may be introduced into the inlet transfer device or inlet transfer reaction device 10 via the first supplementary inlet or port 13 and/or via the second supplementary inlet or port 15.

(24) Other embodiments are contemplated wherein the inlet transfer device or inlet transfer reaction device 10 may comprise further inlets or ports. It is also contemplated that the direction of flow of e.g. a reagent or other gas or liquid through the first supplementary inlet or port 13 may be changed or reversed so that the first supplementary inlet or port 13 may in fact operate as an outlet. Similarly, the direction of flow of e.g. a reagent or other gas or liquid through the second supplementary inlet or port 15 may be changed or reversed so that the second supplementary inlet or port 15 may in fact operate as an outlet.

(25) According to an embodiment the inlet transfer device or inlet transfer reaction device 10 may comprise a Field Asymmetric Ion Mobility Spectrometry (“FAIMS”) device, an atmospheric pressure drift tube, a drift region, a separation region, an ion mobility spectrometer or separator (“IMS”) or another device for separating particles and/or ions according to a physico-chemical property such as mass, mass to charge ratio, ion mobility, differential ion mobility or collision cross section.

(26) A further embodiment is contemplated wherein at least a portion or substantially the whole of the outer housing of the inlet transfer device or inlet transfer reaction device 10 may be (optically) transparent to allow ions and/or particles within the inlet transfer device or inlet transfer reaction device 10 to be subjected to direct illumination via, for example, one or more vacuum ultra-violet (“VUV”) lamps or a source of visible or infra-red radiation. The one or more vacuum ultra-violet (“VUV”) lamps (or other sources of photons) may be provided so as to surround a central region of the inlet transfer device or inlet transfer reaction device 10. As a result, ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10 may be subjected to secondary activation by radiation from one or more vacuum ultra-violet (“VUV”) lamps or other sources of ultra-violet photons or one or more sources of visible or infra-red photons.

(27) It will be apparent, therefore, that it is not essential that the secondary activation device comprises a second laser source. For example, it should be understood that non-laser sources of photons may be utilised in order to illuminate ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10 and hence to subject ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10 to secondary activation. Accordingly, the secondary activation device may comprise a non-laser source of photons for photo-activating ions and/or neutral particles within the inlet transfer device or inlet transfer reaction device 10. The non-laser source of photons may comprise a VUV lamp or a UV LED.

(28) According to an embodiment the first laser source 1 may be activated, energised or otherwise turned ON and one or more first laser beam(s), pulse(s) of electromagnetic radiation or pulse(s) of photons 4 may be focussed down on to the sample target. The impact of the photons upon the target sample surface may result in a plume of target material being generated or otherwise being ablated or desorbed from the surface of the sample target.

(29) The plume of target material may comprise analyte ions, neutral analyte molecules and matrix ions and/or matrix molecules (if a matrix is optionally added to the target sample). It will be understood, however, that it is not essential for a matrix or other reagent to be added to the target sample and indeed a particularly beneficial effect of the various disclosed embodiments is that the target sample may be ionised and analysed in a substantially unmodified or natural state i.e. wherein no matrix or other reagent is added to the target sample prior to initial ionisation, ablation or desorption by the first or primary laser source 1. This is particularly beneficial in terms of simplicity, efficiency and avoiding toxicity issues in relation to the sample which may, for example, comprise in vivo tissue.

(30) The plume of analyte or target material, optionally including matrix ions and/or matrix molecules may be arranged to enter the inlet transfer device or inlet transfer reaction device 10 via the first main inlet or port 12. The first main inlet or port 12 may comprise a capillary or heated capillary or a portion of a capillary or heated capillary. The capillary or heated capillary or the portion of the capillary or heated capillary may have a curved or non-linear portion.

(31) As shown in FIG. 1, the inlet transfer device or inlet transfer reaction device 10 may comprise a central portion or region which may comprise a capillary, capillary tube, tube or other hollow transfer member. Analyte material and analyte ions may be arranged to flow into the housing of the inlet transfer device or inlet transfer reaction device 10 via the main inlet or port 12 so that the analyte material, analyte ions and optionally matrix ions and/or neutral matrix molecules flow along and through the central portion, housing or region of the inlet transfer device or inlet transfer reaction device 10. Any analyte material, analyte ions, matrix ions or neutral matrix molecules together with any new particles or ions which may be generated within the inlet transfer device or inlet transfer reaction device 10 by the process of secondary activation may then be directed so as to exit the inlet transfer device or inlet transfer reaction device 10 via the main outlet or port 14. The first main outlet or port 14 may comprise a capillary or heated capillary or a portion of a capillary or heated capillary. The capillary or heated capillary or the portion of the capillary or heated capillary may have a curved or non-linear portion.

(32) The main outlet or port 14 may be connected to or may otherwise be provided in close proximity to a restriction orifice or atmospheric pressure interface 19 of an analytical device. The restriction orifice or atmospheric pressure interface 19 may, therefore, provide an interface between an ambient, atmospheric or above atmospheric pressure region and a lower pressure or sub-atmospheric pressure region. The restriction orifice or atmospheric pressure interface 19 may lead directly into an initial or first vacuum chamber or housing 16 of a mass spectrometer 17, ion mobility spectrometer, differential ion mobility spectrometer or other analytical device or analytical analyser.

(33) The speed at which target material, analyte or other material from the plume passes through the central portion of the inlet transfer device or inlet transfer reaction device 10 may be calculated or otherwise determined based upon inter alia the internal diameter of the inlet transfer device or inlet transfer reaction device 10 and the internal diameter of the restriction orifice or atmospheric pressure interface 19.

(34) When the plume of target material or analyte is captured or otherwise retained within the inlet transfer device or inlet transfer reaction device 10 or when the plume of target material or analyte is arranged to be transmitted through the inlet transfer device or inlet transfer reaction device 10, the second or secondary laser 6 may then be fired or otherwise activated one or more times so as to generate a laser beam or one or more laser pulses 7 which are directed along at least a portion of the central portion of the inlet transfer device or inlet transfer reaction device 10.

(35) In the embodiment shown in FIG. 1 the second laser beam or pulse(s) 7 are directed along the central portion or central axis of the inlet transfer device or inlet transfer reaction device 10 in a direction which is substantially counter to the direction of travel or flow of target material or analyte through the central portion or housing of the inlet transfer device or inlet transfer reaction device 10. However, other embodiments are contemplated wherein the orientation of the second laser source 6 or the direction of flow through the inlet transfer device or inlet transfer reaction device 10 may be reversed so that the second laser beam or pulse(s) 7 are directed along the central portion or central axis of the inlet transfer device or inlet transfer reaction device 10 in a direction which is substantially the same as the direction of travel or flow of target material or analyte through the central portion or housing of the inlet transfer device or inlet transfer reaction device 10.

(36) A particularly beneficial aspect of the various embodiments is that there is arranged to be a substantial, increased, maximum, controllable or optimum overlap between the secondary laser beam or pulse(s) 7 and analyte and/or neutral particles and/or matrix and/or analyte or other ions so that the process of secondary activation is substantially enhanced, optimised or otherwise controlled.

(37) Embodiments are contemplated wherein the degree of spatial overlap and/or the temporal extent of overlap between photons emitted from the secondary activation source or device and ions and/or neutral particles within the housing of the transfer device may be varied, altered or controlled. For example, during the course of an experimental run it may be desired to subject ions and/or neutral particles to different degrees of secondary activation. The intensity and mark/space ratio of photons emitted from the second laser 6 or other secondary activation device may be varied and numerous different modes of operation of the second laser 6 or other secondary device are contemplated.

(38) Another beneficial aspect of the various disclosed embodiments is that the process of secondary activation may be performed by directing potentially harmful laser (or other) irradiation from the second laser source 6 (or other form of secondary activation device) away from the target sample and in particular away from the surface of the target sample. As a result, the various embodiments provide a safer way of performing secondary activation of e.g. ions and/or neutral particles and ensure that potentially dangerous pulses of laser radiation are kept away from the target sample which may comprise in vivo tissue or a living organism or from a user who may be in close proximity to the target sample.

(39) Another beneficial aspect of the various embodiments is that there is no requirement or necessity to use conventional MALDI matrices (such as 2,5-dihydroxybenzoic acid (“DHB”), α-cyano-4-hydroxycinnamic acid (“CCA”) or sinapinic acid (“SA”) together with an organic base such as pyridine (“Py”), tributylamine (“TBA”) or N,N-dimethylethylenediamine (“DMED”)) with the sample surface. Accordingly, problems of chemical toxicity of the target sample can be avoided. For example, according to an embodiment IR MALDI may be performed wherein the matrix comprises water or another non-toxic or inert matrix. The non-toxic or inert matrix (e.g. water or another substance) may exist naturally within the sample or may be added in situ.

(40) According to an embodiment the laser beam or pulse(s) 7 from the second laser source 6 (or photons from another secondary activation source or device) may be arranged so as to perform multiple internal reflections within the inlet transfer device or inlet transfer reaction device 10. Furthermore, high fluence focal points may be generated within the transfer capillary or transfer device 10 thereby further maximizing the overlap between analyte material or ions, optional matrix material or matrix ions and the secondary activation laser beam or pulse(s) 7.

(41) According to an embodiment one or more matrices or other reagents may be introduced into the inlet transfer device or inlet transfer reaction device 10 via either the first supplementary inlet 13 and/or the second supplementary inlet 15. The one or more matrices or other reagents may be introduced into the inlet transfer device or inlet transfer reaction device 10 in order to enhance the ionisation of neutral particles within the inlet transfer device or inlet transfer reaction device 10 or to enhance another process or reaction or photo-activation effect within the inlet transfer device or inlet transfer reaction device 10.

(42) Analyte ions and/or neutral particles and/or matrix or other ions within the inlet transfer device or inlet transfer reaction device 10 may also be subjected to other various reactions. For example, analyte ions and/or neutral particles may be subjected to fast photochemical oxidation of proteins (“FPOP”) type reactions. Fast photochemical oxidation of proteins (“FPOP”) is a chemical footprinting method whereby exposed amino-acid residues are covalently labelled by oxidation with hydroxyl radicals produced by the photolysis (i.e. photodissociation or photodecomposition) of hydrogen peroxide. Although oxidation via hydroxyl radicals induces unfolding in proteins on a time scale of milliseconds or longer, FPOP is designed to limit *OH exposure to 1 μs or less by employing a pulsed laser for initiation to produce radicals and a radical-scavenger to limit their lifetimes.

(43) Gas-phase hydrogen/deuterium exchange (“HDX”) reactions may also be performed within the inlet transfer device or inlet transfer reaction device 10. For example, gaseous ND.sub.3 may be introduced into the inlet transfer reaction device 10 such that analyte ions undergo hydrogen/deuterium exchange as they mix with the ND.sub.3 and pass towards the outlet 14 of the inlet transfer reaction device 10 and the inlet 19 of the mass spectrometer 17. The extent of deuterium labelling may be controlled by varying the quantity of ND.sub.3 and/or the speed at which the analyte ions pass through the inlet transfer reaction device 10. Hydrogen/deuterium exchange of protein ions is highly sensitive to protein conformation and enables the detection of conformers.

(44) According to an embodiment hydrogen/deuterium exchange reagents (gas or liquid) may be introduced via the first supplementary inlet 13 and/or via the second supplementary inlet 15. If an hydrogen/deuterium exchange reaction is performed within the inlet transfer device or inlet transfer reaction device 10 then the second laser source may either not be provided or may not be activated.

(45) The second laser 6 may be used to provide de-clustering, photo-fragmentation, photo-activation or photo-dissociation of ions within the inlet transfer device or inlet transfer reaction device 10 by processes such as Electron Capture Dissociation (“ECD”) and/or Electron Transfer Dissociation (“ETD”) as a result of free electron generation. The fragment ions resulting from fragmentation, activation, declustering or dissociation processes such as Electron Capture Dissociation (“ECD”) and/or Electron Transfer Dissociation (“ETD”) may be mass analysed and may provide useful information which is helpful to confirm the precise identity of analyte ions.

(46) Various embodiments are contemplated wherein ions and/or neutral particles are subjected to secondary activation and/or a reaction, fragmentation or dissociation process within the housing of an inlet transfer device or inlet transfer reaction device 10. Controlling the flow of gas, liquid or reagent into the first supplementary inlet 13 and/or into the second supplementary inlet 15 provides a way of changing the velocity of particles and/or ions passing along or through the inlet transfer device or inlet transfer reaction device 10. If the flow rate of particles and/or ions passing through the inlet transfer device or inlet transfer reaction device 10 is slowed down then the particles and/or ions may be subjected to a greater number of laser shots or laser pulses from the second laser 6 and hence may be subjected to a greater degree of secondary activation. Conversely, if the flow rate of particles and/or ions passing through the inlet transfer device or inlet transfer reaction device 10 is increased then the particles and/or ions may be subjected to a fewer number of laser shots or laser pulses from the second laser 6 and hence may be subjected to lesser degree of secondary activation. One or more electric fields may be applied across one or more regions or portions of the inlet transfer device or inlet transfer reaction device 10 in order to increase, decrease, vary or control the speed or transit time of charged particles or ions through the inlet transfer device or inlet transfer reaction device 10. Optionally, one or more transient DC voltages may be applied across or along one or more regions or portions of the inlet transfer device or inlet transfer reaction device 10 in order to increase, decrease, vary or control the speed or transit time of charged particles or ions through the inlet transfer device or inlet transfer reaction device 10. The flow rate of particles and ions through the inlet transfer device or inlet transfer reaction device 10 may also be controlled electro-mechanically by, for example, controlling the size of a restriction aperture and/or by diverting, controlling or directing flow through different paths through the inlet transfer device or inlet transfer reaction device 10.

(47) 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.