METHOD OF MASS SPECTROMETRY

Description

[0001] With the decoding of the 20-30,000 genes that compose the human genome, emphasis has switched to the identification of the translated gene products that comprise the proteome. Mass spectrometry has firmly established itself as the primary technique for identifying proteins due to its unparalleled speed, sensitivity and specificity. Strategies can involve either analysis of the intact protein or more commonly digestion of the protein using a specific protease that cleaves at predictable residues along the peptide backbone. This provides smaller stretches of peptide sequence which are more amenable to analysis via mass spectrometry.

[0002] The mass spectrometry technique providing the highest degree of specificity and sensitivity is Electrospray Ionisation ("ESI") interfaced to a tandem mass spectrometer allowing fragmentation studies by low energy MS/MS. These experiments involve separation of the complex digest mixture by microcapillary liquid chromatography with on-line mass spectral detection using automated acquisition modes whereby conventional MS and MS/MS spectra are collected in a data dependant manner. This information can be used directly to search databases for matching sequences leading to identification of the parent protein. This approach has recently allowed the identification of proteins that are present at low endogenous concentrations. However, often the limiting factor for identification of the protein is not the quality of the MS/MS spectrum produced but is the initial identification of the multiply charged peptide precursor ion in the MS mode. This is due to the level of background chemical noise, largely singly charged in nature, which may be produced in the ion source of the mass spectrometer. Fig. 1 shows a conventional mass spectrum and shows how doubly charged species may be obscured in a singly charged background.

[0003] It would be desirable to reduce the singly charged chemical noise thereby allowing the mass spectrometer to specifically target multiply charged peptide related ions. The ability to be able to discriminate against singly charged ions in favour of multiply charged ions would be particularly advantageous for the study of protein digests.

[0004] With an Electrospray Ionisation orthogonal acceleration Time of flight ("ESI-oaTOF") mass spectrometer it is known to flavour the transmission of multiply charged species in preference to singly charged species by increasing the discriminator voltage and/or lowering the gain. The orthogonal acceleration Time of Flight mass spectrometer counts the arrival of ions using a Time to Digital Converter ("TDC") which has a discriminator threshold. The voltage pulse of a single ion must be high enough to trigger the discriminator and so register the arrival of an ion. The detector producing the voltage may be an electron multiplier or Microchannel Plate detector ("MCP"). These detectors are charge sensitive so the size of signal they produce increases with increasing charge state. Discrimination in favour of higher charge states may therefore be accomplished by either increasing the discriminator voltage level of the TDC and/or by lowering the detector gain or a combination of both. Fig. 2A shows a conventional mass spectrum obtained with an orthogonal acceleration Time of Flight mass spectrometer and Fig. 2B shows a corresponding mass spectrum obtained by lowering the gain of the ion detector. As can be seen from comparing Figs. 2A and 2B one of the disadvantages of this technique is that lowering the gain and/or increasing the discriminator level decreases the detection efficiency for the desired charge state and hence the sensitivity is reduced. Furthermore, it is impossibly pick out an individual charge state according to this method. All that can be done is to reduce the efficiency of detection of lower charge states with respect to higher charge states.

[0005] It is therefore desired to be able to preferentially transmit multiply charged ions whilst attenuating singly charged ions without substantially reducing sensitivity.

[0006] R. Guevremont et al, International Journal of Mass Spectrometry 193 (1999) 45-56 [XP 004365756] discloses a high-field asymmetric waveform ion mobility spectrometer comprising an ion trapping region.

[0007] Rapid Communications in Mass Spectrometry, 14, 1907-1913 (2000) [XP 002370070] discloses a study on the radial stratification of ions as a function of mass to charge ratio during collisional cooling in an ion trap.

[0008] According to the present invention there is provided a method of mass spectrometry as claimed in claim 1.

[0009] Preferably, the product P x T is at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400,

[0010]  410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 or 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500 or 10000 mbar-ms.

[0011] Preferably, the product P x T is less than 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 or 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500 or 10000 mbar-ms.

[0012] Preferably, T falls within a range selected from the group consisting of: (i) 50-100 µs; (ii) 100-150 µs; (iii) 150-200 µs; (iv) 200-250 µs; (v) 250-300 µs; (vi) 300-350 µs; (vii) 350-400 µs; (viii) 400-450 µs; (ix) 450-500 µs; (x) 500-550 µs; (xi) 550-600 µs; (xii) 600-650 µs; (xiii) 650-700 µs; (xiv) 700-750 µs; (xv) 750-800 µs (xvi) 800-850 µs; (xvii) 850-900 µs; (xviii) 900-950 µs; and (xix) 950-1000 µs. Preferably, T falls within a range selected from the group consisting of: (i) 1-2 ms; (ii) 2-3 ms; (iii) 3-4 ms; (iv) 4-5 ms; (v) 5-6 ms; (vi) 6-7 ms; (vii) 7-8 ms; (viii) 8-9 ms; and (ix) 9-10 ms. Preferably, T falls within a range selected from the group consisting of: (i) 10-15 ms; (ii) 15-20 ms; (iii) 20-25 ms; (iv) 25-30 ms; (v) 30-35 ms; (vi) 35-40 ms; (vii) 40-45 ms; (viii) 45-50 ms; (ix) 50-55 ms; (x) 55-60 ms; (xi) 60-65 ms; (xii) 65-70 ms; (xiii) 70-75 ms; (xiv) 75-80 ms; (xv) 80-85 ms; (xvi) 85-90 ms; (xvii) 90-95 ms; and (xviii) 95-100 ms. Preferably, T falls within a range selected from the group consisting of: (i) 100-110 ms; (ii) 110-120 ms; (iii) 120-130 ms; (iv) 130-140 ms; (v) 140-150 ms; (vi) 150-160 ms; (vii) 160-170 ms; (viii) 170-180 ms; (ix) 180-190 ms; and (x) 190-200 ms. Preferably, T falls within a range selected from the group consisting of: (i) 200-250 ms; (ii) 250-300 ms; (iii) 300-350 ms; (iv) 350-400 ms; (v) 400-450 ms; (vi) 450-500 ms; (vii) 500-550 ms; (viii) 550-600 ms; (ix) 600-650 ms; (x) 650-700 ms; (xi) 700-750 ms; (xii) 750-800 ms; (xiii) 800-850 ms; (xiv) 850-900 ms; (xv) 900-950 ms; and (xvi) 950-1000 ms.

[0013] Preferably, T is at least than: (i) 50 µs; (ii) 60 µs (iii) 70 µs; (iv) 80 µs; (v) 90 µs; or (vi) 100 µs. Preferably, T is at least: (i) 200 µs; (ii) 300 µs (iii) 400 µs; (iv) 500 µs; (v) 600 µs; (vi) 700 µs; (vii) 800 µs; (viii) 900 µs; or (ix) 1000 µs. Preferably, T is at least: (i) 2 ms; (ii) 3 ms (iii) 4 ms; (iv) 5 ms; (v) 6 ms; (vi) 7 ms; (vii) 8 ms; (viii) 9 ms; or (ix) 10 ms. Preferably, T is at least: (i) 20 ms; (ii) 30 ms (iii) 40 ms; (iv) 50 ms; (v) 60 ms; (vi) 70 ms; (vii) 80 ms; (viii) 90 ms; or (ix) 100 ms. Preferably, T is at least: (i) 100 ms; (ii) 200ms (iii) 300 ms; (iv) 400 ms; (v) 500 ms; (vi) 600 ms; (vii) 700 ms; (viii) 800 ms; or (ix) 900 ms. Preferably, T is at least: (i) 1s; (ii) 2s; (iii) 3s; (iv) 4s; (v) 5s; (vi) 6s; (vii) 8s; (viii) 9s; or (ix) 10s. Preferably, T is less than: (i) 10s; (ii) 9s; (iii) 8s; (iv) 7s; (v) 6s; (vi) 5s; (vii) 4s; (viii) 3s; or (ix) 2s.

[0014] Preferably, T is less than: (i) 1000 ms; (ii) 900ms (iii) 800 ms; (iv) 700 ms; (v) 600 ms; (vi) 500 ms; (vii) 400 ms; (viii) 300 ms; or (ix) 200 ms. Preferably, T is less than: (i) 100 ms; (ii) 90ms (iii) 80 ms; (iv) 70 ms; (v) 60 ms; (vi) 50 ms; (vii) 40 ms; (viii) 30 ms; or (ix) 20 ms. Preferably, T is less than: (i) 10 ms; (ii) 9 ms (iii) 8 ms; (iv) 7 ms; (v) 6 ms; (vi) 5 ms; (vii) 4 ms; (viii) 3 ms; or (ix) 2 ms. Preferably, T is less than: (i) 1000 µs; (ii) 900 µs (iii) 800 µs; (iv) 700 µs; (v) 600 µs; (vi) 500 µs; (vii) 400 µs; (viii) 300 µs; or (ix) 200 µs. Preferably, T is less than: (i) 100 µs; (ii) 90 µs (iii) 80 µs; (iv) 70 µs; (v) 60 µs; or (vi) 50 µs.

[0015] Preferably, P falls within a range selected from the group consisting of: (i) 0.01-0.02 mbar; (ii) 0.02-0.03 mbar; (iii) 0.03-0.04 mbar; (iv) 0.04-0.05 mbar; (v) 0.05-0.06 mbar; (vi) 0.06-0.07 mbar; (vii) 0.07-0.08 mbar; (viii) 0.08-0.09 mbar; and (ix) 0.09-0.10 mbar. Preferably, P falls within a range selected from the group consisting of: (i) 0.1-0.2 mbar; (ii) 0.2-0.3 mbar; (iii) 0.3-0.4 mbar; (iv) 0.4-0.5 mbar; (v) 0.5-0.6 mbar; (vi) 0.6-0.7 mbar; (vii) 0.7-0.8 mbar; (viii) 0.8-0.9 mbar; and (ix) 0.9-1.0 mbar. Preferably, P falls within a range selected from the group consisting of: (i) 1-2 mbar; (ii) 2-3 mbar; (iii) 3-4 mbar; (iv) 4-5 mbar; (v) 5-6 mbar; (vi) 6-7 mbar; (vii) 7-8 mbar; (viii) 8-9 mbar; and (ix) 9-10 mbar. Preferably, P falls within a range selected from the group consisting of: (i) 10-20 mbar; (ii) 20-30 mbar; (iii) 30-40 mbar; (iv) 40-50 mbar; (v) 50-60 mbar; (vi) 60-70 mbar; (vii) 70-80 mbar; (viii) 80-90 mbar; and (ix) 90-100 mbar.

[0016] Preferably, P is at least: (i) 0.01 mbar; (ii) 0.02 mbar; (iii) 0.03 mbar; (iv) 0.04 mbar; (v) 0.05 mbar; (vi) 0.06 mbar; (vii) 0.07 mbar; (viii) 0.08 mbar; or (ix) 0.09 mbar. Preferably, P is at least: (i) 0.1 mbar; (ii) 0.2 mbar; (iii) 0.3 mbar; (iv) 0.4 mbar; (v) 0.5 mbar; (vi) 0.6 mbar; (vii) 0.7 mbar; (viii) 0.8 mbar; or (ix) 0.9 mbar. Preferably, P is at least: (i) 1 mbar; (ii) 2 mbar; (iii) 3 mbar; (iv) 4 mbar; (v) 5 mbar; (vi) 6 mbar; (vii) 7 mbar; (viii) 8 mbar; or (ix) 9 mbar. Preferably, P is at least: (i) 10 mbar; (ii) 20 mbar; (iii) 30 mbar; (iv) 40 mbar; (v) 50 mbar; (vi) 60 mbar; (vii) 70 mbar; (viii) 80 mbar; (ix) 90 mbar; or (x) 100 mbar.

[0017] Preferably, P is less than: (i) 100 mbar; (ii) 90 mbar; (iii) 80 mbar; (iv) 70 mbar; (v) 60 mbar; (vi) 50 mbar; (vii) 40 mbar; (viii) 30 mbar; or (ix) 20 mbar. Preferably, P is less than: (i) 10 mbar; (ii) 9 mbar; (iii) 8 mbar; (iv) 7 mbar; (v) 6 mbar; (vi) 5 mbar; (vii) 4 mbar; (viii) 3 mbar; or (ix) 2 mbar. Preferably, P is less than: (i) 1 mbar; (ii) 0.9 mbar; (iii) 0.8 mbar; (iv) 0.7 mbar; (v) 0.6 mbar; (vi) 0.5 mbar; (vii) 0.4 mbar; (viii) 0.3 mbar; or (ix) 0.2 mbar. Preferably, P is less than: (i) 0.10 mbar; (ii) 0.09 mbar; (iii) 0.08 mbar; (iv) 0.07 mbar; (v) 0.06 mbar; (vi) 0.05 mbar; (vii) 0.04 mbar; (viii) 0.03 mbar; or (ix) 0.02 mbar.

[0018] Preferably, P is selected from the group consisting of: (i) > 0.01 mbar; (ii) > 0.05 mbar; (iii) > 0.1 mbar; (iv) > 0.2 mbar; (v) > 0.5 mbar; (vi) > 1 mbar; (vii) > 2 mbar; (viii) > 5 mbar; and (ix) > 10 mbar.

[0019] The sample of ions preferably comprises at least some ions having similar or substantially the same mass to charge ratios but different charge states. The at least some ions may have similar or substantially the same mass to charge ratios preferably wherein the mass to charge ratios differ by less than: (i) 20 mass to charge units; (ii) 15 mass to charge units; (iii) 10 mass to charge units; (iv) 5 mass to charge units; (v) 4 mass to charge units; (vi) 3 mass to charge units; (vii) 2 mass to charge units; and (viii) 1 mass to charge unit, wherein 1 mass to charge unit equals 1 dalton per unit of electronic charge.

[0020] The sample of ions may comprise a plurality of ionised molecules, the molecules comprising a plurality of different biopolymers, proteins, peptides, polypeptides, oligonucleotides, oligionucleosidas, amino acids, carbohydrates, sugars, lipids, fatty acids, vitamins, hormones, portions or fragments of DNA, portions or fragments of cDNA, portions or fragments of RNA, portions or fragments of mRNA, portions or fragments of TRNA, polyclonal antibodies, monoclonal antibodies, ribonucleases, enzymes, metabolites, polysaccharides, phosphorolated peptides, phosphorolated proteins, glycopeptides, glycoproteins or steroids.

[0021] According to another embodiment of the present invention, there is provided a method of mass spectrometry comprising:

providing a sample of singly charged ions and doubly charged ions having similar mass to charge ratios;

onwardly transmitting doubly charged ions whilst at least partially relatively attenuating singly charged ions; and

mass analysing the doubly charged ions.

[0022] Preferably, the AC or RF ion guide comprises electrodes and the AC or RF ion guide has a central longitudinal axis, and wherein the combination of pressure and trapping time is such that singly charged ions are forced radially outwards from the central longitudinal axis whereas multiply charged ions are caused to forced towards the central longitudinal axis.

[0023] The singly charged ions are preferably substantially ejected from or lost from the AC or RF ion guide, whereas at least some preferably a majority of the multiply charged ions are substantially retained within the AC or RF ion guide.

[0024] Preferably, one or more of the following groups of ions are substantially ejected from or lost from the AC or RF ion guide: (i) ions having 2 charges; (ii) ions having 3 charges; (iii) ions having 4 charges; (iv) ions having 5 charges; (v) ions having 6 charges; (vi) ions having 7 charges; (vii) ions having 8 charges; (viii) ions having 9 charges; (ix) ions having 10 charges; (x) ions having 11 charges; (xi) ions having 12 charges; (xii) ions having 13 charges; (xiii) ions having 14 charges; (xiv) ions having 15 charges; (xv) ions having 16 charges; (xvi) ions having 17 charges; (xvii) ions having 18 charges; (xviii) ions having 19 charges; (xix) ions having 20 charges; (xx) ions having 21 charges; (xxi) ions having 22 charges; and (xxii) ions having more than 22 charges.

[0025] Preferably, one or more of the following groups of ions are substantially retained with the AC or RF ion guide: (i) ions having 2 charges; (ii) ions having 3 charges; (iii) ions having 4 charges; (iv) ions having 5 charges; (v) ions having 6 charges; (vi) ions having 7 charges; (vii) ions having 8 charges; (viii) ions having 9 charges; (ix) ions having 10 charges; (x) ions having 11 charges; (xi) ions having 12 charges; (xii) ions having 13 charges; (xiii) ions having 14 charges; (xiv) ions having 15 charges; (xv) ions having 16 charges; (xvi) ions having 17 charges; (xvii) ions having 18 charges; (xviii) ions having 19 charges; (xix) ions having 20 charges; (xx) ions having 21 charges; (xxi) ions having 22 charges; and (xxii) ions having more than 22 charges.

[0026] According to another embodiment of the present invention, unwanted singly charged background ions are removed from a mixture of singly charged background ions and multiply charged analyte ions, the method comprising:

transmitting the mixture of ions to the AC or RF ion guide;

trapping the ions within the AC or RF ion guide maintained at the pressure P;

setting the period of time T during which the ions are trapped within the AC or RF ion guide at a value such that at least 50%, 60%, 70%, 80%, 90% or more than 90% of said singly charged ions will be substantially ejected from or lost from the AC or RF ion guide whereas at least 50%, 60%, 70%, 80%, 90% or more than 90% of said multiply charged ions will be substantially maintained within the AC or RF ion guide.

[0027] According to another embodiment of the present invention, there is provided a method of removing or attenuating singly and/or doubly charged ions from a mixture of at least singly, doubly and triply charged ions.

[0028] According to another aspect of the present invention there is provided a mass spectrometer as claimed in claim 25.

[0029] The mass spectrometer preferably further comprises an ion source for generating mainly molecular or pseudo-molecular ions.

[0030] The ion source may comprise an atmospheric pressure ionization source such as an ion source selected from the group comprising: (i) an Electrospray ionisation ("EST") ion source; (ii) an Atmospheric Pressure Chemical Ionisation ("APCI") ion source; (iii) an Atmospheric Pressure Photo Ionisation ("APPI") ion source; (iv) an atmospheric pressure Matrix Assisted Laser Desorption Ionisation ("MALDI") ion source; and (v) an Inductively Coupled Plasma ("ICP") ion source. Alternatively, the ion source may comprise a non-atmospheric pressure ionization source such as an ion source selected from the group consisting of: (i) a Fast Atom Bombardment ("FAB") ion source; (ii) a Liquid Secondary Ions Mass Spectrometry ("LSIMS") ion source; (iii) a Matrix Assisted Laser Desorption Ionisation ("MALDI") ion source; (iv) a Matrix Assisted Laser Desorption ("MALDI") ion source in combination with a collision cell for collisionally cooling ions; (v) a Laser Desorption Ionisation ("LDI") ion source; (vi) an Electron Impact ("EI") ion source; and (vii) a Chemical Ionization ("CI") ion source.

[0031] Preferably, the AC or RF ion guide comprises a multipole rod set e.g. a quadrupole rod set, a hexapole rod set, an octopole rod set or a rod set having ten or more rods.

[0032] Alternatively, the AC or RF ion guide may comprise a plurality of electrodes having apertures through which the ions are transmitted. For example, the AC or RF ion guide may comprise an ion tunnel having a plurality of electrodes each having substantially the same size aperture or an ion funnel having a plurality of electrodes wherein the size of the apertures becomes progressively smaller or larger.

[0033] According to another embodiment the AC or RF ion guide may comprises a double helix arrangement of electrodes.

[0034] According to a yet further embodiment the AC or RF ion guide may comprise a plurality of plates stacked adjacent to each other.

[0035] The mass spectrometer preferably comprises a mass analyzer such as a Time of Flight mass analyzer, a quadrupole mass analyzer, a 2D or 3D ion trap, a Fourier Transform mass spectrometer or a Fourier Transform Ion Cyclotron Resonance mass spectrometer.

[0036] The mass spectrometer preferably further comprises a further AC or RF ion guide arranged in a further vacuum chamber. A quadrupole mass filter and/or a collision cell may be arranged in a yet further vacuum chamber intermediate the vacuum chamber(s) housing the AC or RF ion guide(s) and the vacuum chamber housing the mass analyzer. The ion source may comprise an atmospheric pressure ion source and the mass analyzer may comprise a Time of Flight mass analyzer.

[0037] Preferably, the further AC or RF ion guide comprises: (i) a multipole rod set; (ii) an, ion funnel comprising a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of the apertures becomes progressively smaller or larger; (iii) an ion tunnel comprising a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of the apertures remains substantially constant; (iv) a double helix arrangement of electrodes; and (v) a stack of plates wherein adjacent electrodes are connected to opposite phases of an AC or RF supply.

[0038] According to another embodiment of the present invention, there is provided a mass spectrometer comprising:

an ion source;

a first AC or RF ion guide disposed in an upstream ion guide vacuum chamber, the first AC or RF ion guide being maintained at a pressure P1:

a second AC or RF ion guide disposed in a downstream ion guide vacuum chamber, the second AC or RF ion guide being maintained at a pressure P2; and

a mass analyser disposed in a further vacuum chamber, the further vacuum chamber being disposed downstream of the upstream ion guide vacuum chamber and the downstream ion guide vacuum chamber;

wherein, in use, ions are arranged to be trapped in the first AC or RF ion guide for a time T1 and/or ions are arranged to be trapped in the second AC or RF ion guide for a time T2 wherein P1 x T1 is at least 1 mbar-ms and/or P2 x T2 is at least 1 mbar-ms.

[0039] Preferably, the AC or RF ion guide and/or the further AC or RF ion guide comprises: (i) a multipole rod set; (ii) an ion funnel comprising a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of the apertures becomes progressively smaller or larger; (iii) an ion tunnel comprising a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of the apertures remains substantially constant; (iv) a double helix arrangement of electrodes; and (v) a stack of plates wherein adjacent electrodes are connected to opposite phases of an AC or RF supply.

[0040] According to another embodiment of the present invention, there is provided a method of mass spectrometry comprising:

operating an AC or RF device in a first mode wherein the AC of RF device acts as an ion guide to substantially transmit ions received at an entrance to the device through to an exit of the device; and

operating the AC or RF device in a second mode wherein the AC of RF device acts as an ion trap to substantially trap ions within the device and to substantially prevent the ions from exiting the device, wherein in the second mode the AC or RF device is maintained at a pressure P and ions are trapped within the AC or RF device for a period of time T, wherein the product P x T is at least 1 mbar-ms.

[0041] Preferably, the period of time T is a continuous or substantially continuous period of time. Alternatively, the period of time T is an accumulative period of time.

[0042] According to the preferred embodiment ions having a chosen charge state are selected from a mixture of ions having differing charge states by trapping the ions in an RF device for a period of time and in the presence of a buffer gas at a particular pressure.

[0043] Ions generated from an Electrospray Ionisation source, for example, typically contain a mixture of charge states. These ions are usually generated at atmospheric pressure and admitted to the mass spectrometer through means of a pumping aperture that forms part of a differentially pumped vacuum system. In normal operation these ions continually stream through an RF device into regions of lower pressure by means of further differentially pumped regions which lead in turn to a mass analyser housed in an analyser vacuum chamber. The resulting mass spectrum therefore contains ions of all the charge states generated in the ionisation region of the instrument.

[0044] If an electrode is placed at the exit of the RF device then ions can be trapped by raising the potential of this gate electrode higher than the body or reference DC potential of the AC or RF device. During this trapping phase ions are preferably still able to enter the device at the upstream end through the differential pumping aperture and hence ions can build up in concentration. If the electrode voltage is reduced then the accumulated ions will be released. By adjusting the pressure in the trapping device it is possible to vary the ratio of singly to multiply charged species.

[0045] Various embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Fig. 1 shows how doubly charged ions may be obscured amongst a background of singly charged ions in a typical mass spectrum;

Fig. 2A shows a conventional mass spectrum and Fig. 2B shows a corresponding mass spectrum obtained by lowering the detector gain;

Fig. 3A shows a schematic drawing of a collisional trapping charge state selector device according to the preferred embodiment and Fig. 3B shows a timing diagram for the voltage applied to an electrode adjacent the exit of the AC or RF device;

Fig. 4A shows a mass spectrum of ions obtained by guiding ions through the AC or RF device without trapping the ions when the AC or RF device was maintained at a pressure of 1.4 mbar, Fig. 4B shows a mass spectrum of ions obtained by guiding ions through the AC or RF device without trapping the ions when the AC or RF device was maintained at a pressure of 2.7 mbar, Fig. 4C shows a mass spectrum obtained wherein ions were trapped at a pressure of 1.4 mbar for 60 ms, and Fig. 4D shows a mass spectrum obtained according to the preferred embodiment wherein ions were trapped within the AC or RF device at a pressure of 2.7 mbar for 60 ms;

Fig. 5A is an expansion of Fig. 4B and Fig. 5B is an expansion of Fig. 5D;

Fig. 6A shows a plot of trapping time against pressure for which the ratio of the intensity of doubly charged ions from Gramacidin-S (m/z 571) to that of singly charged ions from Leucine Enkephalin (m/z 556) was doubled over that for no trapping and Fig. 6B shows a plot of trapping time against pressure for which the ratio of the intensity of triply charged ions from Renin Substrate (m/z 586) to that of singly charged ions from Leucine Enkephalin (m/z 556) was doubled over that for no trapping;

Fig. 7 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.64 mbar;

Fig. 8 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.64 mbar;

Fig. 9 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 1.64 mbar;

Fig. 10 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S^-(m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.95 mbar;

Fig. 11 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.95 mbar;

Fig. 12 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 1.95 mbar;

Fig. 13 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.23 mbar;

Fig. 14 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.23 mbar;

Fig. 15 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 2.23 mbar;

Fig. 16 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.51 mbar;

Fig. 17 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.51 mbar;

Fig. 18 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 2.51 mbar;

Fig. 19 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.86 mbar;

Fig. 20 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.86 mbar; and

Fig. 21 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 2.86 mbar.

[0046] A preferred AC or RF ion guide/ion trap 5 will now be described in relation to Fig. 3A. Ions from an ion source 1 enter an upstream vacuum chamber 2 which may have an optional RF ion guide 3 arranged therein. However, such an ion guide 3 is not essential and may be omitted. The upstream vacuum chamber 2 is pumped by a pump. Ions pass through a differential pumping aperture 9 into an intermediate vacuum chamber 4. Another RF ion guide 5 is preferably provided in the intermediate vacuum chamber 4 and according to one embodiment this AC or RF ion guide 5 may be operated in one mode of operation as an ion trap. Ions may, for example, be trapped in the guide 5 by raising the potential of a differential pumping aperture 6 which separates the intermediate vacuum chamber from a downstream vacuum chamber 7 preferably housing another RF ion guide 8. The electric field resulting from the voltage applied to the differential pumping aperture 6 preferably extends into the downstream region of the intermediate ion guide 5 and hence has the effect of preventing ions from exiting the ion guide 5. A voltage may or may not be applied to an electrode adjacent an upstream end of the intermediate AC or RF ion guide 5. However, since the differential pumping aperture 9 is preferably maintained at a higher DC potential than the reference DC potential of the intermediate AC or RF ion guide 5 then ions are effectively prevented from exiting the AC or RF ion guide 5 via the entrance. Ions entering the AC or RF ion guide 5 quickly become thermalised i.e. lose their kinetic energy and when a trapping voltage is removed the ions preferably exit the intermediate AC or RF ion guide 5 by the repulsive space-charge effect of further ions entering the ion guide 5. Other embodiments are also contemplated especially in relation to ion tunnel ion guides wherein an axial voltage gradient is used to encourage ions to travel through and/or leave the ion guide(s).

[0047] When the potential applied to the differential pumping aperture 6 is lowered, ions may exit the ion guide 5 and pass through the differential pumping aperture 6 into the downstream vacuum chamber 7 which preferably houses a downstream AC or RF ion guide 8. Ions are preferably guided through the downstream vacuum chamber 7 by the ion guide 8 and may then pass through a further differential pumping aperture 10 into an analyser vacuum chamber (not shown) housing a mass analyser (not shown).

[0048] A timing diagram of the voltage applied to the differential pumping aperture 6 or more generally to an exit electrode of the AC or RF ion trap 5 is shown in Fig. 3B. When the differential pumping aperture 6 or the exit to the ion trap 4 is at a voltage V_trap then ions are unable to exit the AC or RF ion trap 5 and hence accumulate in the device 5. When the voltage applied to the exit differential pumping aperture 6 or the exit electrode of the AC or RF ion trap 5 falls to V_extract then ions are allowed to the exit the ion trap 5 and pass to the next stages and subsequently to the ion detector (not shown).

[0049] According to an embodiment the AC or RF ion guide/ion trap 5 is maintained in the intermediate vacuum chamber 4 at a pressure in the range 1-3 mbar. However, according to other embodiments the upstream AC or RF ion guide 3 and/or the downstream AC or RF ion guide 8 may also be used to trap ions therein.

[0050] By varying or appropriately setting (i) the pressure in the trapping region, (ii) the cycle time T_m, (iii) the release width W and (iv) the voltages V_trap and V_extract it is possible to maximise the trapping efficiency and to maximise or optimise the discrimination between singly and multiply charged species.

[0051] By way of illustration Figs. 4A and 4B show the mass spectra obtained when the AC or RF device 5 is operated as an ion guide substantially without trapping ions therein (e.g. the voltage applied to the exit of the AC or RF device 5 is maintained at V_extract. Fig. 4A shows the mass spectrum obtained when the AC or RF device 5 was maintained at a pressure of 1.4 mbar and Fig. 4B shows the mass spectrum obtained when the AC or RF device 5 was maintained at a pressure of 2.7 mbar. In both cases the AC or RF device 5 acted as an ion guide without trapping ions.

[0052] All the experimental results presented in the present application were obtained using an AC or RF device which comprised an ion tunnel. An ion tunnel comprises a plurality of electrodes having preferably circular apertures through which ions are transmitted in use. The ion tunnel may therefore be considered to comprise a plurality of stacked rings. According to an embodiment the ion tunnel comprises two interleaved combed arrangements of electrodes. Adjacent electrodes in the ion tunnel device are supplied with opposite phases of an AC or RF voltage supply. The voltage supply is preferably sinusoidal but other embodiments are contemplated wherein, for example, a square wave or other non-sinusoidal waveform may be applied to the device. The ion tunnel device preferably comprises 10-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90, 90-100 or more than 100 electrodes. Preferably, the vast majority of the electrodes have substantially similar size apertures in contrast to an ion funnel. According to an embodiment at least 75%, 80%, 85%, 90%, 95% or 99% of the electrodes forming the ion tunnel have substantially the same size and/or area internal apertures.

[0053] However, the present invention is not limited to using an ion tunnel ion guide and other AC or RF devices are intended to fall within the scope of the present invention.

[0054] An equimolar mixture of Leucine-Enkephalin (which exhibits a singly charged peak at m/z 556) and Gramacidin-S (which exhibits a doubly charged peak at m/z 571) was infused into the mass spectrometer. The slight difference in intensities between the two species is largely attributable to differing ionisation efficiencies and is normal in Electrospray mass spectrometry.

[0055] Figs. 4C and 4D show mass spectra obtained when the RF device 5 was operated as an ion trap. Ions were trapped within the ion trap 2 for 60 ms in both cases. Fig. 4C shows the mass spectrum obtained when the ions were trapped for 60 ms in the ion trap 5 at a pressure of 1.4 mbar. As is apparent, Fig. 4C is substantially similar to the mass spectra shown in Figs. 4A and 4B.

[0056] Fig. 4D illustrates an embodiment of the present invention and shows the mass spectrum which resulted from mass analysing the ions which emerged from the ion trap 5 when the ion trap 5 was maintained at a pressure of 2.7 mbar and ions were trapped within the ion trap 5 for 60 ms.

[0057] The mass spectra shown in Figs. 4A, 4B and 4C are qualitatively similar and show that the ratio of the intensity of the doubly charged mass peaks at m/z 571 to the ratio of the intensity of the singly charged mass peaks at m/z 556 remained substantially constant. However, when the ions were trapped at 2.7 mbar for 60 ms then as clearly shown in Fig. 4D singly charged ions were significantly attenuated whilst the doubly charged Gramacidin-S ions at m/z 571 were substantially unattenuated.

[0058] Fig. 5A corresponds with the data shown in Fig. 4B and shows the mass spectrum for ions in the mass to charge ratio range 290-580 (as opposed to ions having mass to charge ratios in the range 556-573 as shown in Fig. 4B). Similarly, Fig. 5B corresponds with the data shown in Fig. 4D and shows the mass spectrum for ions in the mass to charge ratio range 290-580 (as opposed to ions having mass to charge ratios in the range 556-573 as shown in Fig. 4D).

[0059] As can be clearly seen from Figs. 5A and 5B singly charged ions present in the sample were rejected from the ion trap 5 when the mixture of ions was trapped at 2.7 mbar for 60 ms whereas doubly charged ions were substantially unattenuated. The peak at mass to charge 297.6 is doubly charged and is substantially unattenuated.

[0060] The reasons for the discrimination against singly charged ions in favour of multiply charged ions will now be discussed below. In particular, the distribution of ions within inhomogeneous RF Fields will now be considered.

[0061] Through consideration of the average force acting on an ion in the inhomogeneous RF fields it can be shown that the time average of the alternating force is finite and is directed towards the region of weaker field independent of the sign of the ionic charge. This quadratic potential Φ can be expressed as:

The corresponding electric field E may be expressed as:

[0062] For a quadrupole rod set λ = -σ and γ = 0, and for a quadrupole ion trap λ = σ and γ = -2σ. For both the quadrupole rod set and the quadrupole ion trap the field is uncoupled in the three directions. Hence, the secular motion is simple harmonic along any given co-ordinate axis.

[0063] Evaluation of the kinetic energy along any given co-ordinate axis, averaged over one period, allows the constant W to be determined, where W is a constant of the secular motion corresponding to the total energy in the system with time-independent conservative forces. That is:

[0064] The maximum kinetic energy in the micro-motion of the ion is equivalent to the pseudo-potential energy eΨ. For a quadrupole ion trap the value of the corresponding effective, or equivalent, potential Ψ is given by:

where m is the mass of the ion, z is the charge of the ion, e is the charge of an electron and ω is the angular frequency of the RF supply.

[0065] Through consideration of the pseudo-potential energy eΨ for multipole rod sets it can also be shown that the effective potential Ψ(R) as a function of the radial distance R is given by:

where V₀ is the peak RF voltage applied to the rods, R₀ in the inscribed radius of the rods, R is the radial distance from the centre and 2N is the number of rods.

[0066] Furthermore, it is known that the pseudo-potential energy eΨ for a stacked ring set is proportional to the exponential function of radial displacement R. The effective potential Ψ(R,Z) as a function of the radial distance R and the axial position Z is given by:

where R₀ is the inscribed radius of the rings, nZ₀ is the ring centre to ring centre separation in the axial direction, I1 is a first order modified Bessel function of the first kind and IO is a zeroth order modified Bessel function of the first kind.

[0067] Through consideration of the effect of ion-molecule collisions in the quadrupole field (F. G. Major and H. G. Dehmelt, Phys. Rev., 1968, 170, 91) it has been shown that when ions of mass m undergo purely elastic collisions within an RF field with relatively cold gas molecules of mass m₀ where m » m₀, the collisions will result in viscous drag which lowers the mean kinetic energy of the ions as a function of time. The authors go on to state that the ion micro-motion is not interrupted by the collisions, but only slightly modified in phase and amplitude, while any secular motion is damped out exponentially.

[0068] The experimental results presented in the present application show that there is an abundance of doubly charged ions relative to that of singly charged ions following the accumulation of ions in a 2D stacked ring ion guide at a pressures of 2.7 mbar (2 torr) for a trapping period of 60 ms. The data shows enhancement of ions with higher charge states (z values) but with the same m/z values as the product of pressure and storage time is increased.

[0069] As already discussed, the effective potential ψ(R) as a function of the radial distance R for a multipole rod set is given by:

Hence by differentiation of the effective potential with respect to R the effective radial field Γ(R) as a function of the radial distance R is given by:

Therefore, the radial force F(R) as a function of the radial distance R on ions with mass m and charge z is equal to zeΓ(R). Hence:

[0070] It will be seen that the radial force F(R) towards the centre is proportional to z²/m. Similarly, the effective potential ψ(R,Z) as a function of the radial distance R and axial position Z for a ring stack set is given by:

[0071] A similar treatment shows that the radial force F(R) towards the centre is again proportional to z²/m. Hence, the radial force is greater for ions of the same mass m with higher charge states z i.e. ions of the same substance with lower m/z values.

[0072] However, it will be seen that the radial force F(R) towards the centre is also proportional to z/(m/z). Hence, the radial force is also greater for ions with the same m/z value but with higher values of the charge state z as has been observed.

[0073] As a consequence of this, ions with the same values of mass to charge ratio (m/z) but with higher charge states (z) will experience a greater force directed towards the centre where the field is weakest. In an environment where ions are free to move, but frequently in collision with lighter gas molecules, ions that experience the greater radial force will eventually migrate and occupy the central space. Ions that experience a smaller radial force will eventually be squeezed out to occupy larger radial positions. This arranging of ions according to the force acting upon them will only take place in situations where the ions lose their secular motion through collisional damping, and where adequate time has been allowed for the whole population of ions to reach a steady state.

[0074] This process by which ions arrange themselves into layers or bands is similar to that which takes place when DNA segments are centrifuged in a caesium chloride density gradient solution to separate out the DNA satellites. In the centrifuge the DNA molecules separate into a number of bands - the main band and three additional bands (satellites). The different satellite bands have different densities depending on whether they are AT-rich or CG-rich segments. This separation of DNA into bands is the result of the different centrifugal forces acting on the different classes of DNA molecules. In a similar manner, ions with the same m/z value, but different z values, will experience different effective radial forces as a result of the effective pseudo-potential well generated by the inhomogeneous RF fields, and will consequentially separate into different bands. Ions with the lower z values will occupy larger radial positions. Hence, these ions are more likely to be lost through collisions with the rods or rings of the ion guide, or not be transmitted through any small orifice arranged along the axis of the ion guide after its exit.

[0075] As has already been explained, a method for enhancing the signal from doubly, triply or more highly charged ions from that of background singly charged ions is particularly advantageous for the study of protein digests. The peptides from protein digests, when ionised by electrospray, often yield an abundance of doubly charged, triply or more highly charged ions. The method, as described above, of first storing ions at elevated pressures in an ion guide or ion trap employing inhomogeneous RF fields provides a means of enhancing the relative abundance of multiply charged ions to that of singly charged ions having the same m/z values. This method can therefore be employed before mass analysis so as to enhance the relative abundance of multiply charged ions to that of singly charged ions at equivalent m/z values within the mass spectrum. The relative enhancement of doubly charged ion abundance to that of singly charged ion abundance becomes very pronounced at pressures above 1.4 mbar (1 torr) for storage times of the order of 60 ms. Hence, the enhancement of doubly charged ion abundance to that of singly charged ion abundance becomes very pronounced when the product of pressure and storage or transit time is greater than 8.4 x 10^-2 mbar-seconds (6 x 10^-2 torr-seconds).

[0076] Figs. 6A and 6B show the results of further investigations into the relationship between trapping time and pressure. Fig. 6A shows a plot of trapping time (ms) against pressure (mbar) for which the ratio of the intensity of doubly charged ions from Gramacidin-S (m/z 571) to that of the singly charged ions from Leucine Enkephalin (m/z 556) is doubled over that for no trapping. The particular data points are:

Pressure (P)	Trapping time (T)	P x T
1.95 mbar	89 ms	173.55 mbar-ms
2.23 mbar	60 ms	133.80 mbar-ms
2.51 mbar	42.5 ms	106.68 mbar-ms
2.86 mbar	21 ms	60.06 mbar-ms

[0077] Pressure and trapping time appear to be exponentially related. An empirically derived relationship for the results shown in Fig. 6A is:

where T is the trapping time in ms and P is the pressure in mbar.

[0078] Fig. 6B shows a plot of trapping time (ms) against pressure (mbar) for which the ratio of the intensity of the triply charged ions from Renin Substrate (m/z 586) to that of the singly charged ions from Leucine Enkephalin (m/z 556) is doubled over that for no trapping. The particular data points are:

Pressure (P)	Trapping time (T)	P x T
1.64 mbar	89 ms	145.96 mbar-ms
1.95 mbar	50 ms	97.50 mbar-ms
2.23 mbar	32 ms	71.36 mbar-ms
2.51 mbar	21 ms	52.71 mbar-ms
2.86 mbar	7 ms	20.02 mbar-ms

[0079] Pressure and trapping time again appear to be exponentially related. An empirically derived relationship for the results shown in Fig. 6B is:

where T is the trapping time in ms and P is the pressure in mbar.

[0080] These results show that by modestly increasing the pressure the required trapping time can be drastically reduced.

[0081] Fig. 7 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.64 mbar, Fig. 8 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.64 mbar and Fig. 9 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 1.64 mbar.

[0082] Fig. 10 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.95 mbar, Fig. 11 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 1.95 mbar and Fig. 12 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 1.95 mbar.

[0083] Fig. 13 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.23 mbar, Fig. 14 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.23 mbar and Fig. 15 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 2.23 mbar.

[0084] Fig. 16 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin,(m/z 556) ions at 2.51 mbar, Fig. 17 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.51 mbar and Fig. 18 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 2.51 mbar.

[0085] Fig. 19 shows the effect of storage or trapping time on the intensity of doubly charged Gramacidin-S (m/z 571) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.86 mbar, Fig. 20 shows the effect of storage or trapping time on the intensity of triply charged Renin Substrate (m/z 586) ions and singly charged Leucine Enkephalin (m/z 556) ions at 2.86 mbar and Fig. 21 shows the ratio of intensities of: (i) doubly charged Gramacidin-S ions (m/z 571) to singly charged Leucine Enkephalin (m/z 556) ions; and (ii) triply charged Renin Substrate (m/z 586) ions to singly charge Leucine Enkephalin (m/z 556) ions, as a function of storage or trapping time at 2.86 mbar.

[0086] It will be seen that in some instances the ion signal can first increase before eventually decreasing as the trapping time is increased. This effect can be observed to a greater or lesser extent in Figs, 7, 10, 13, 14, 17, 19 and 20. It is thought that the increase in signal intensity is due to ions beginning to migrate towards the centre of the pseudo-potential well as a result of frequent collisions with the lighter gas molecules. This ion migration is likely to be the precursor to the process in which ions with higher values of z²/m eventually displace ions which have lower values of z²/m and occupy the central space. Ions that accumulate in the central region are more likely to be transmitted through the exit of the ion guide and to the ion detection system. Hence, ions that initially collapse into the centre of the pseudo-potential well may be expected to show a corresponding increase in signal intensity. In fact, by careful selection of pressure and trapping time, it is possible to enhance the ratio of the intensity of the multiply charged ions with respect to that of singly charged ions with similar m/z values and simultaneously increase the absolute intensity of the multiply charged ions.

[0087] If a mass spectrometer is being switched between two modes of operation or is being switched from transmitting ions of one m/z value to those of a different m/z value there will be a period of time for which the mass spectrometer will not be able to receive and transmit ions. In this period of time ions may advantageously be trapped in the AC or RF ion guide/ion trap and then released when the mass spectrometer is ready to accept these ions thereby gaining the advantage of the extra sensitivity that is observed when ions are trapped according to the preferred embodiment described above.

[0088] The preferred embodiment also looks particularly useful for preferentially transmitting ions having a large number of charges. For example, horse heart myoglobin has a molecular mass of 16951.48 and ions may in some conditions have 8 or 9 charges or in other conditions the ions may have between 10-28 charges. Experimental data suggests that with highly charged ions preferentially transmission of multiply charged ions in favour of lower or singly charged ions occurs down to pressures P and trapping times T wherein the product P x T is 1 mbar-ms. Experimental data suggests that at or above the product of P x T equalling 1 mbar-ms the beneficial effect of the selective enhancement of multiply charged ions is observed.

[0089] Although the preferred embodiment above has been described mainly in relation to preferentially transmitting doubly or triply charged ions as opposed to singly charged ions, the enhancement of highly charged ions to those of e.g. singly charged ions also becomes pronounced at lower products of pressure and storage or transit time.

[0090] The preferred embodiment can be used for removing background ions from a mixture of ions, wherein the mixture of ions comprises a plurality of different biopolymers, proteins, peptides, polypeptides, oligionucleotides, oligionucleosides, amino acids, carbohydrates, sugars, lipids, fatty acids, vitamins, hormones, portions or fragments of DNA, portions or fragments of cDNA, portions or fragments of RNA, portions or fragments of mRNA, portions or fragments of tRNA, polyclonal antibodies, monoclonal antibodies, ribonucleases, enzymes, metabolites, polysaccharides, phosphorolated peptides, phosphorolated proteins, glycopeptides, glycoproteins or steroids.

[0091] Although the present invention has been described with reference to preferred embodiments and other arrangements, 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.

Claims

1. A method of mass spectrometry comprising a step of trapping a sample of ions in an AC or RF ion guide (5) in the presence of a gas at a pressure P for a period of time T,
said method being characterized by including a step of enhancing the relative proportion or abundance of multiply charged ions to singly charged ions in said sample of ions, the product P X T being at least 1 mbar-ms. .

2. A method as claimed in claim 1, wherein the product P x T is at least: 2 mbar-ms; 3 mbar-ms; 4 mbar-ms; 5 mbar-ms; 6 mbar-ms; 7 mbar-ms; 8 mbar-ms; 9 mbar-ms; 10 mbar-ms; 15 mbar-ms; 20 mbar-ms; 25 mbar-ms; 30 mbar-ms; 35 mbar-ms; 40 mbar-ms; 45 mbar-ms; 50 mbar-ms; 55 mbar-ms; 60 mbar-ms; 65 mbar-ms; 70 mbar-ms; 75 mbar-ms; 80 mbar-ms; 85 mbar-ms; 90 mbar-ms; 95 mbar-ms; 100 mbar-ms; 110 mbar-ms; 120 mbar-ms; 130 mbar-ms; 140 mbar-ms; 150 mbar-ms; 160 mbar-ms; 170 mbar-ms; 180 mbar-ms; 190 mbar-ms; 200 mbar-ms; 210 mbar-ms; 220 mbar-ms; 230 mbar-ms; 240 mbar-ms; 250 mbar-ms; 260 mbar-ms; 270 mbar-ms; 280 mbar-ms; 290 mbar-ms; 300 mbar-ms; 310 mbar-ms; 320 mbar-ms; 330 mbar-ms; 340 mbar-ms; 350 mbar-ms; 360 mbar-ms; 370 mbar-ms; 380 mbar-ms; 390 mbar-ms; 400 mbar-ms; 410 mbar-ms; 420 mbar-ms; 430 mbar-ms; 440 mbar-ms; 450 mbar-ms; 460 mbar-ms; 470 mbar-ms; 480 mbar-ms; 490 mbar-ms; 500 mbar-ms; 550 mbar-ms; 600 mbar-ms; 650 mbar-ms; 700 mbar-ms; 750 mbar-ms; 800 mbar-ms; 850 mbar-ms; 900 mbar-ms; 950 mbar-ms; 1000 mbar-ms; 1100 mbar-ms; 1200 mbar-ms; 1300 mbar-ms; 1400 mbar-ms; 1500 mbar-ms; 1600 mbar-ms; 1700 mbar-ms; 1800 mbar-ms; 1900 mbar-ms; 2000 mbar-ms; 2500 mbar-ms; 3000 mbar-ms; 3500 mbar-ms; 4000 mbar-ms; 4500 mbar-ms; 5000 mbar-ms; 5500 mbar-ms; 6000 mbar-ms; 6500 mbar-ms; 7000 mbar-ms; 7500 mbar-ms; 8000 mbar-ms; 85.00 mbar-ms; 9000 mbar-ms; 9500 mbar-ms; or 10000 mbar-ms.

3. A method as claimed in claim 1 or 2, wherein the product P x T is less than: 2 mbar-ms; 3 mbar-ms; 4 mbar-ms; 5 mbar-ms; 6 mbar-ms; 7 mbar-ms; 8 mbar-ms; 9 mbar-ms; 10 mbar-ms; 15 mbar-ms; 20 mbar-ms; 25 mbar-ms; 30 mbar-ms; 35 mbar-ms ; 40 mbar-ms; 45 mbar-ms; 50 mbar-ms; 55 mbar-ms; 60 mbar-ms; 65 mbar-ms; 70 mbar-ms; 75 mbar-ms; 80 mbar-ms; 85 mbar-ms; 90 mbar-ms; 95 mbar-ms; 100 mbar-ms; 110 mbar-ms; 120 mbar-ms; 130 mbar-ms; 140 mbar-ms; 150 mbar-ms; 160 mbar-ms; 170 mbar-ms; 180 mbar-ms; 190 mbar-ms; 200 mbar-ms; 210 mbar-ms; 220 mbar-ms; 230 mbar-ms; 240 mbar-ms; 250 mbar-ms; 260 mbar-ms; 270 mbar-ms; 280 mbar-ms; 290 mbar-ms; 300 mbar-ms; 310 mbar-ms; 320 mbar-ms; 330 mbar-ms; 340 mbar-ms; 350 mbar-ms; 360 mbar-ms; 370 mbar-ms; 380 mbar-ms; 390 mbar-ms; 400 mbar-ms; 410 mbar-ms; 420 mbar-ms; 430 mbar-ms; 440 mbar-ms; 450 mbar-ms; 460 mbar-ms; 470 mbar-ms; 480 mbar-ms; 490 mbar-ms; 500 mbar-ms; 550 mbar-ms; 600 mbar-ms; 650 mbar-ms; 700 mbar-ms; 750 mbar-ms; 800 mbar-ms; 850 mbar-ms; 900 mbar-ms; 950 mbar-ms; 1000 mbar-ms; 1100 mbar-ms; 1200 mbar-ms; 1300 mbar-ms; 1400 mbar-ms; 1500 mbar-ms; 1600 mbar-ms; 1700 mbar-ms; 1800 mbar-ms; 1900 mbar-ms; 2000 mbar-ms; 2500 mbar-ms; 3000 mbar-ms; 3500 mbar-ms; 4000 mbar-ms; 4500 mbar-ms; 5000 mbar-ms; 5500 mbar-ms; 6000 mbar-ms; 6500 mbar-ms; 7000 mbar-ms; 7500 mbar-ms; 8000 mbar-ms; 8500 mbar-ms; 9000 mbar-ms; 9500 mbar-ms; or 10000 mbar-ms.

4. A method as claimed in claim 1, 2 or 3, wherein T falls within a range selected from the group consisting of: 50-100 µs; 100-150 µs; 150-200 µs; 200-250 µs; 250-300 µs; 300-350 µs; 350-400 µs; 400-450 µs; 450-500 µs; 500-550 µs; 550-600 µs; 600-650 µs; 650-700 µs; 700-750 µs; 750-800 µs; 800-850 µs; 850-900 µs; 900-950 µs; 950-1000 µs; 1-2 ms; 2-3 ms; 3-4 ms; 4-5 ms; 5-6 ms; 6-7 ms; 7-8 ms; 8-9 ms; 9-10 ms; 10-15 ms; 15-20 ms; 20-25 ms; 25-30 ms; 30-35 ms; 35-40 ms; 40-45 ms; 45-50 ms; 50-55 ms; 55-60 ms; 60-65 ms; 65-70 ms; 70-75 ms; 75-80 ms; 80-85 ms; 85-90 ms; 90-95 ms; 95-100 ms; 100-110 ms; 110-120 ms; 120-130 ms; 130-140 ms; 140-150 ms; 150-160 ms; 160-170 ms; 170-180 ms; 180-190 ms; 190-200 ms; 200-250 ms; 250-300 ms; 300-350 ms; 350-400 ms; 400-450 ms, 450-500 ms; 500-550 ms; 550-600 ms; 600-650 ms; 650-700 ms; 700-750 ms; 750-800 ms; 800-850 ms; 850-900 ms; 900-950 ms; and 950-1000 ms.

5. A method as claimed in claim 1, 2 or 3, wherein T is at least: 50 µs; 60 µs; 70 µs; 80 µs; 90 µs; 100 µs; 200 µs; 300 µs; 400 µs; 500 µs; 600 µs; 700 µs; 800 µs; 900 µs; 1000 µs; 2 ms; 3 ms; 4 ms; 5 ms; 6 ms; 7 ms; 8 ms; 9 ms; 10 ms; 20 ms; 30 ms; 40 ms; 50 ms; 60 ms; 70 ms; 80 ms; 90 ms; 100 ms; 100 ms; 200ms; 300 ms; 400 ms; 500 ms; 600 ms; 700 ms; 800 ms; 900 ms; 1 s; 2 s; 3 s; 4 s; 5 s; 6 s; 8 s; 9 s; or 10 s.

6. A method as claimed in claim 1, 2, 3 or 5, wherein T is less than: 10 s; 9 s; 8 s; 7 s; 6 s; 5 s; 4 s; 3 s; 2 s; 1000 ms; 900 ms; 800 ms; 700 ms; 600 ms; 500 ms; 400 ms; 300 ms; 200 ms; 100 ms; 90ms; 80 ms; 70 ms; 60 ms; 50 ms; 40 ms; 30 ms; 20 ms; 10 ms; 9 ms; 8 ms; 7 ms; 6 ms; 5 ms; 4 ms; 3 ms; 2 ms; 1000 µs; 900 µs; 800 µs; 700 µs; 600 µs; 500 µs; 400 µs; 300 µs; 200 µs; 100 µs; 90 µs; 80 µs; 70 µs; 60 µs; or 50 µs.

7. A method as claimed in any preceding claim, wherein P falls within a range selected from the group consisting of: 0.01-0.02 mbar; 0.02-0.03 mbar; 0.03-0.04 mbar; 0.04-0.05 mbar; 0.05-0.06 mbar; 0.06-0.07 mbar; 0.07-0.08 mbar; 0.08-0.09 mbar; 0.09-0.10 mbar; 0.1-0.2 mbar; 0.2-0.3 mbar; 0.3-0.4 mbar; 0.4-0.5 mbar; 0.5-0.6 mbar; 0.6-0.7 mbar; 0.7-0.8 mbar; 0.8-0.9 mbar; 0.9-1.0 mbar; 1-2 mbar; 2-3 mbar; 3-4 mbar; 4-5 mbar; 5-6 mbar; 6-7 mbar; 7-8 mbar; 8-9 mbar; 9-10 mbar; 10-20 mbar; 20-30 mbar; 30-40 mbar; 40-50 mbar; 50-60 mbar; 60-70 mbar; 70-80 mbar; 80-90 mbar; and 90-100 mbar.

8. A method as claimed in any of claims 1-6, wherein P is at least: 0.01 mbar; 0.02 mbar; 0.03 mbar; 0.04 mbar; 0.05 mbar; 0.06 mbar; 0.07 mbar; 0.08 mbar; 0.09 mbar; 0.1 mbar; 0.2 mbar; 0.3 mbar; 0.4 mbar; 0.5 mbar; 0.6 mbar; 0.7 mbar; 0.8 mbar; 0.9 mbar; 1 mbar; 2 mbar; 3 mbar; 4 mbar; 5 mbar; 6 mbar; 7 mbar; 8 mbar; 9 mbar; 10 mbar; 20 mbar; 30 mbar; 40 mbar; 50 mbar; 60 mbar; 70 mbar; 80 mbar; 90 mbar; or 100 mbar.

9. A method as claimed in any preceding claim, wherein P is less than: 100 mbar; 90 mbar; 80 mbar; 70 mbar; 60 mbar; 50 mbar; 40 mbar; 30 mbar; 20 mbar; 10 mbar; 9 mbar; 8 mbar; 7 mbar; 6 mbar; 5 mbar; 4 mbar; 3 mbar; 2 mbar; 1 mbar; 0.9 mbar; 0.8 mbar; 0.7 mbar; 0.6 mbar; 0.5 mbar; 0.4 mbar; 0.3 mbar; 0.2 mbar; 0.10 mbar; 0.09 mbar; 0.08 mbar; 0.07 mbar; 0.06 mbar; 0.05 mbar; 0.04 mbar; 0.03 mbar; or 0.02 mbar.

10. A method as claimed in any preceding claim, wherein P is selected from the group consisting of: (i) > 0.01 mbar; (ii) > 0.05 mbar; (iii) > 0.1 mbar; (iv) > 0.2 mbar; (v) > 0.5 mbar; (vi) > 1 mbar; (vii) > 2 mbar; (viii) > 5 mbar; and (ix) > 10 mbar.

11. A method as claimed in any preceding claim, wherein said sample of ions comprises at least some ions having similar or substantially the same mass to charge ratios but different charge states.

12. A method as claimed in claim 11, wherein said at least some ions having similar or substantially the same mass to charge ratios have mass to charge ratios which differ by less than: (i) 20 mass to charge units; (ii) 15 mass to charge units; (iii) 10 mass to charge units; (iv) 5 mass to charge units; (v) 4 mass to charge units; (vi) 3 mass to charge units; (vii) 2 mass to charge units; and (viii) 1 mass to charge unit, wherein 1 mass to charge unit equals 1 dalton per unit of electronic charge.

13. A method as claimed in any preceding claim, wherein said sample of ions comprises a plurality of ionised molecules, said molecules comprising a plurality of different biopolymers, proteins, peptides, polypeptides, oligionucleotides, oligionucleosides, amino acids, carbohydrates, sugars, lipids, fatty acids, vitamins, hormones, portions or fragments of DNA, portions or fragments of cDNA, portions or fragments of RNA, portions or fragments of mRNA, portions or fragments of tRNA, polyclonal antibodies, monoclonal antibodies, ribonucleases, enzymes, metabolites, polysaccharides, phosphorolated peptides, phosphorolated proteins, glycopeptides, glycoproteins or steroids.

14. A method as claimed in any preceding claim, wherein the AC or RF ion guide comprises electrodes and the AC or RF ion guide has a central longitudinal axis, and wherein the combination of pressure and trapping time is such that singly charged ions are forced radially outwards from said central longitudinal axis whereas multiply charged ions are forced towards said central longitudinal axis.

15. A method as claimed in any preceding claim, wherein said singly charged ions are substantially ejected from or lost from said AC or RF ion guide (5).

16. A method as claimed in any preceding claim, wherein at least some or a majority of said multiply charged ions are substantially retained within said AC or RF ion guide (5).

17. A method as claimed in any of claims 1-15, wherein one or more of the following groups of ions are substantially ejected from or lost from said AC or RF ion guide: (i) ions having 2 charges; (ii) ions having 3 charges; (iii) ions having 4 charges; (iv) ions having 5 charges; (v) ions having 6 charges; (vi) ions having 7 charges; (vii) ions having 8 charges; (viii) ions having 9 charges; (ix) ions having 10 charges; (x) ions having 11 charges; (xi) ions having 12 charges; (xii) ions having 13 charges; (xiii) ions having 14 charges; (xiv) ions having 15 charges; (xv) ions halving 16 charges; (xvi) ions having 17 charges; (xvii) ions having 18 charges; (xviii) ions having 19 charges; (xix) ions having 20 charges; (xx) ions having 21 charges; (xxi) ions having 22 charges; and (xxii) ions having more than 22 charges.

18. A method as claimed in any of claims 1-15, wherein one or more of the following groups of ions are substantially retained with said AC or RF ion guide: (i) ions having 2 charges; (ii) ions having 3 charges; (iii) ions having 4 charges; (iv) ions having 5 charges; (v) ions having 6 charges; (vi) ions having 7 charges; (vii) ions having 8 charges; (viii) ions having 9 charges; (ix) ions having 10 charges; (x) ions having 11 charges; (xi) ions having 12 charges; (xii) ions having 13 charges; (xiii) ions having 14 charges; (xiv) ions having 15 charges; (xv) ions having 16 charges; (xvi) ions having 17 charges; (xvii) ions having 18 charges; (xviii) ions having 19 charges; (xix) ions having 20 charges; (xx) ions having 21 charges; (xxi) ions having 22 charges; and (xxii) ions having more than 22 charges.

19. A method as claimed in claim 1, wherein unwanted singly charged background ions are removed from a mixture of singly charged background ions and multiply charged analyte ions, said method comprising:

transmitting said mixture of ions to said AC or RF ion guide (5);

trapping said ions within said AC or RF ion guide maintained at said pressure P; and

setting said period of time T during which the ions are trapped within the AC or RF ion guide at a value such that at least 50%, 60%, 70%, 80%, 90% or more than 90% of said singly charged ions will be substantially ejected from or lost from the AC or RF ion guide whereas at least 50%, 60%, 70%, 80%, 90% or more than 90% of said multiply charged ions will be substantially maintained within said AC or RF ion guide.

20. A method as claimed in claim 1, comprising removing or attenuating singly and/or doubly charged ions from a mixture of at least singly, doubly and triply charged ions.

21. A method as claimed in claim 1 comprising:

providing a sample of singly charged ions and doubly charged ions having similar mass to charge ratios;

onwardly transmitting said doubly charged ions whilst at least partially relatively attenuating said singly charged ions; and

mass analysing said doubly charged ions.

22. A method as claimed in claim 1 comprising:

operating said AC or RF ion guide (5) in a first mode to substantially transmit ions received at an entrance to the ion guide through to an exit of the ion guide; and

operating said AC or RF ion guide in a second mode wherein said ion guide acts as an ion trap to substantially trap ions within said ion guide and to substantially prevent said ions from exiting the ion guide, wherein in said second mode the AC or RF ion guide enhances the relative proportion or abundance of multiply charged ions in the sample.

23. A method as claimed in claim 22, wherein said period of time T is a continuous or substantially continuous period of time.

24. A method as claimed in claim 22, wherein said period of time T is an accumulative period of time.

25. A mass spectrometer comprising:

an ion source (1);

a vacuum chamber (4) housing an AC or RF ion guide (5) maintained in use at a pressure P;

an electrode (6), wherein in a first mode of operation a potential applied to said electrode (6) causes a sample of ions to be substantially trapped within said AC or RF ion guide (5) and wherein in a second mode of operation the potential applied to said electrode (6) allows ions to be released from said AC or RF ion guide (5);

a further vacuum chamber housing a mass analyzer; and

said mass spectrometer is characterized by also comprising:

control means arranged to enhance the relative proportion or abundance of multiply charged ions to singly charged ions in said sample of ions by controlling a period of time T that ions are trapped within said AC or RF ion guide (5) such that the product P x T is at least 1 mbar-ms.

26. A mass spectrometer as claimed in claim 25, comprising an ion source (1) for generating mainly molecular or pseudo-molecular ions.

27. A mass spectrometer as claimed in claim 25 or 26, wherein said ion source (1) comprises an atmospheric pressure ionization source.

28. A mass spectrometer as claimed in claim 27, wherein said ion source (1) is selected from the group comprising: (i) an Electrospray ionisation ("ESI") ion source; (ii) an Atmospheric Pressure Chemical Ionisation ("APCI") ion source; (iii) an Atmospheric Pressure Photo Ionisation ("APPI") ion source; (iv) an atmospheric pressure Matrix Assisted Laser Desorption Ionization ("MALDI") ion source; and (v) an Inductively Coupled Plasma ("ICP") ion source.

29. A mass spectrometer as claimed in claim 25 or 26, wherein said ion source (1) comprises a non-atmospheric pressure ionization source.

30. A mass spectrometer as claimed in claim 29, wherein said ion source (1) is selected from the group consisting of: (i) a Fast Atom Bombardment ("FAB") ion source; (ii) a Liquid Secondary Ions Mass Spectrometry ("LSIMS") ion source; (iii) a Matrix Assisted Laser Desorption Ionisation ("MALDI") ion source; (iv) a Matrix Assisted Laser Desorption (MALDI") ion source in combination with a collision cell for collisionally cooling ions; (v) a Laser Desorption Ionisation ("LDI") ion source; (vi) an Electron Impact ("EI") ion source; and (vii) a Chemical Ionisation ("CI") ion source.

31. A mass spectrometer as claimed in any of claims 25-30, wherein said AC or RF ion guide (5) comprises a multipole rod set.

32. A mass spectrometer as claimed in claim 31, wherein said multipole rod set comprises a quadrupole rod set, a hexapole rod set, an octopole rod set or a rod set having ten or more rods.

33. A mass spectrometer as claimed in any of claims 25-30, wherein said AC or RF ion guide (5) comprises a plurality of electrodes having apertures through which said ions are transmitted.

34. A mass spectrometer as claimed in claim 33, wherein said AC or RF ion guide (5) comprises an ion tunnel having a plurality of electrodes each having substantially the.same size aperture.

35. A mass spectrometer as claimed in claim 33, wherein said AC or RF ion guide (5) comprises an ion funnel having a plurality of electrodes wherein the size of the apertures becomes progressively smaller or larger.

36. A mass spectrometer as claimed in any of claims 25-30, wherein said AC or RF ion guide (5) comprises a double helix arrangement of electrodes.

37. A mass spectrometer as claimed in any of claims 25-30, wherein said AC or RF ion guide (5) comprises a plurality of plates stacked adjacent to each other.

38. A mass spectrometer as claimed in any of claims 25-37, further comprising a mass analyser.

39. A mass spectrometer as claimed in claim 38, wherein said mass analyser is selected from the group consisting of: (i) a Time of Flight mass analyser; (ii) a quadrupole mass analyser; (iii) a 2D or 3D ion trap; (iv) a Fourier Transform mass spectrometer; and (v) a Fourier Transform Ion Cyclotron Resonance mass spectrometer.

40. A mass spectrometer as claimed in any of claims 25-39, further comprising a further AC or RF ion guide (8) arranged in a further vacuum chamber (7).

41. A mass spectrometer as claimed in any of claims 25-40, further comprising a quadrupole mass filter and/or a collision cell arranged in a yet further vacuum chamber intermediate the vacuum chamber(s) (4,7) housing said AC or RF ion guide(s) (5,8) and the vacuum chamber housing the mass analyzer.

42. A mass spectrometer as claimed in claim 40, wherein said further AC or RF ion guide (8) comprises: (i) a multipole rod set; (ii) an ion funnel comprising a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of said apertures becomes progressively smaller or larger; (iii) an ion tunnel comprising a plurality of electrodes having apertures therein through which ions are transmitted, wherein the diameter of said apertures remains substantially constant; (iv) a double helix arrangement of electrodes; and (v) a stack of plates wherein adjacent electrodes are connected to opposite phases of an AC or RF supply.

Ansprüche

1. Massenspektrometrisches Verfahren, das einen Schritt des Einfangens einer Probe von Ionen in einer Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz in der Gegenwart eines Gases bei einem Druck P während einer Zeitdauer T umfasst, wobei das Verfahren dadurch gekennzeichnet ist, dass es einen Schritt enthält, um den relativen Anteil oder die relative Häufigkeit von mehrfach geladenen Ionen gegenüber einfach geladenen Ionen in der Probe von Ionen zu erhöhen, wobei das Produkt P x T mindestens 1 mbar-ms beträgt.

2. Verfahren nach Anspruch 1, wobei das Produkt P x T mindestens beträgt: 2 mbar-ms; 3 mbar-ms; 4 mbar-ms; 5 mbar-ms; 6 mbar-ms; 7 mbar-ms; 8 mbar-ms; 9 mbar-ms; 10 mbar-ms; 15 mbar-ms; 20 mbar-ms; 25 mbar-ms; 30 mbar-ms; 35 mbar-ms; 40 mbar-ms; 45 mbar-ms; 50 mbar-ms; 55 mbar-ms; 60 mbar-ms;65 mbar-ms; 70 mbar-ms; 75 mbar-ms; 80 mbar-ms; 85 mbar-ms; 90 mbar-ms; 95 mbar-ms; 100 mbar-ms; 110 mbar-ms; 120 mbar-ms; 130 mbar-ms; 140 mbar-ms; 150 mbar-ms; 160 mbar-ms; 170 mbar-ms; 180 mbar-ms; 190 mbar-ms; 200 mbar-ms; 210 mbar-ms; 220 mbar-ms; 230 mbar-ms; 240 mbar-ms; 250 mbar-ms; 260 mbar-ms; 270 mbar-ms; 280 mbar-ms; 290 mbar-ms; 300 mbar-ms; 310 mbar-ms; 320 mbar-ms; 330 mbar-ms; 340 mbar-ms; 350 mbar-ms; 360 mbar-ms; 370 mbar-ms; 380 mbar-ms; 390 mbar-ms; 400 mbar-ms; 410 mbar-ms; 420 mbar-ms; 430 mbar-ms; 440 mbar-ms; 450 mbar-ms; 460 mbar-ms; 470 mbar-ms; 480 mbar-ms; 490 mbar-ms; 500 mbar-ms; 550 mbar-ms; 600 mbar-ms; 650 mbar-ms; 700 mbar-ms; 750 mbar-ms; 800 mbar-ms; 850 mbar-ms; 900 mbar-ms; 950 mbar-ms; 1000 mbar-ms; 1100 mbar-ms; 1200 mbar-ms; 1300 mbar-ms; 1400 mbar-ms; 1500 mbar-ms; 1600 mbar-ms; 1700 mbar-ms; 1800 mbar-ms; 1900 mbar-ms; 2000 mbar-ms; 2500 mbar-ms; 3000 mbar-ms; 3500 mbar-ms; 4000 mbar-ms; 4500 mbar-ms; 5000 mbar-ms; 5500 mbar-ms; 6000 mbar-ms; 6500 mbar-ms; 7000 mbar-ms; 7500 mbar-ms; 8000 mbar-ms; 8500 mbar-ms; 9000 mbar-ms; 9500 mbar-ms; oder 10000 mbar-ms.

3. Verfahren nach Anspruch 1 oder 2, wobei das Produkt P x T kleiner ist als: 2 mbar-ms; 3 mbar-ms; 4 mbar-ms; 5 mbar-ms; 6 mbar-ms; 7 mbar-ms; 8 mbar-ms; 9 mbar-ms; 10 mbar-ms; 15 mbar-ms; 20 mbar-ms; 25 mbar-ms; 30 mbar-ms; 35 mbar-ms; 40 mbar-ms; 45 mbar-ms; 50 mbar-ms; 55 mbar-ms; 60 mbar-ms;65 mbar-ms; 70 mbar-ms; 75 mbar-ms; 80 mbar-ms; 85 mbar-ms; 90 mbar-ms; 95 mbar-ms; 100 mbar-ms; 110 mbar-ms; 120 mbar-ms; 130 mbar-ms; 140 mbar-ms; 150 mbar-ms; 160 mbar-ms; 170 mbar-ms; 180 mbar-ms; 190 mbar-ms; 200 mbar-ms; 210 mbar-ms; 220 mbar-ms; 230 mbar-ms; 240 mbar-ms; 250 mbar-ms; 260 mbar-ms; 270 mbar-ms; 280 mbar-ms; 290 mbar-ms; 300 mbar-ms; 310 mbar-ms; 320 mbar-ms; 330 mbar-ms; 340 mbar-ms; 350 mbar-ms; 360 mbar-ms; 370 mbar-ms; 380 mbar-ms; 390 mbar-ms; 400 mbar-ms; 410 mbar-ms; 420 mbar-ms; 430 mbar-ms; 440 mbar-ms; 450 mbar-ms; 460 mbar-ms; 470 mbar-ms; 480 mbar-ms; 490 mbar-ms; 500 mbar-ms; 550 mbar-ms; 600 mbar-ms; 650 mbar-ms; 700 mbar-ms; 750 mbar-ms; 800 mbar-ms; 850 mbar-ms; 900 mbar-ms; 950 mbar-ms; 1000 mbar-ms; 1100 mbar-ms; 1200 mbar-ms; 1300 mbar-ms; 1400 mbar-ms; 1500 mbar-ms; 1600 mbar-ms; 1700 mbar-ms; 1800 mbar-ms; 1900 mbar-ms; 2000 mbar-ms; 2500 mbar-ms; 3000 mbar-ms; 3500 mbar-ms; 4000 mbar-ms; 4500 mbar-ms; 5000 mbar-ms; 5500 mbar-ms; 6000 mbar-ms; 6500 mbar-ms; 7000 mbar-ms; 7500 mbar-ms; 8000 mbar-ms; 8500 mbar-ms; 9000 mbar-ms; 9500 mbar-ms; oder 10000 mbar-ms.

4. Verfahren nach Anspruch 1, 2 oder 3, wobei T innerhalb eines Bereiches fällt, der ausgewählt ist aus der Gruppe, die besteht aus: 50-100 µs; 100-150 µs; 150-200 µs; 200-250 µs; 250-300 µs; 300-350 µs; 350-400 µs; 400-450 µs; 450-500 µs; 500-550 µs; 550-600 µs; 600-650 µs; 650-700 µs; 700-750 µs; 750-800 µs; 800-850 µs; 850-900 µs; 900-950 µs; 950-1000 µs; 1-2 ms; 2-3 ms; 3-4 ms; 4-5 ms; 5-6 ms; 6-7 ms; 7-8 ms; 8-9 ms; 9-10 ms; 10-15 ms; 15-20 ms; 20-25 ms; 25-30 ms; 30-35 ms; 35-40 ms; 40-45 ms; 45-50 ms; 50-55 ms; 55-60 ms; 60-65 ms; 65-70 ms; 70-75 ms; 75-80 ms; 80-85 ms; 85-90 ms; 90-95 ms; 95-100 ms; 100-110 ms; 110-120 ms; 120-130 ms; 130-140 ms; 140-150 ms; 150-160 ms; 160-170 ms; 170-180 ms; 180-190 ms; 190-200 ms; 200-250 ms; 250-300 ms; 300-350 ms; 350-400 ms; 400-450 ms; 450-500 ms; 500-550 ms; 550-600 ms; 600-650 ms; 650-700 ms; 700-750 ms; 750-800 ms; 800-850 ms; 850-900 ms; 900-950 ms; und 950-1000 ms.

5. Verfahren nach Anspruch 1, 2 oder 3, wobei T mindestens ist: 50 µs; 60 µs; 70 µs; 80 µs; 90 µs; 100 µs; 200 µs; 300 µs; 400 µs; 500 µs; 600 µs; 700 µs; 800 µs; 900 µs; 1000 µs; 2 ms; 3 ms; 4 ms; 5 ms; 6 ms; 7 ms; 8 ms; 9 ms; 10 ms; 20 ms; 30 ms; 40 ms; 50 ms; 60 ms; 70 ms; 80 ms; 90 ms; 100 ms; 200 ms; 300 ms; 400 ms; 500 ms; 600 ms; 700 ms; 800 ms; 900 ms; 1 s; 2 s; 3 s; 4 s; 5 s; 6 s; 8 s; 9 s; oder 10 s.

6. Verfahren nach Anspruch 1, 2, 3 oder 5, wobei T kleiner ist als: 10 s; 9 s; 8 s; 7 s; 6 s; 5 s; 4 s; 3 s; 2 s; 1000 ms; 900 ms; 800 ms; 700 ms; 600 ms; 500 ms; 400 ms; 300 ms; 200 ms; 100 ms; 90 ms; 80 ms; 70 ms; 60 ms; 50 ms; 40 ms; 30 ms; 20 ms; 10 ms; 9 ms; 8 ms; 7 ms; 6 ms; 5 ms; 4 ms; 3 ms; 2 ms; 1000 µs; 900 µs; 800 µs; 700 µs; 600 µs; 500 µs; 400 µs; 300 µs; 200 µs; 100 µs; 90 µs; 80 µs; 70 µs; 60 µs; oder 50 µs.

7. Verfahren nach einem vorhergehenden Anspruch, wobei P innerhalb eines Bereiches fällt, der ausgewählt ist aus der Gruppe, die besteht aus: 0,01-0,02 mbar; 0,01-0,02 mbar; 0,02-0,03 mbar; 0,03-0,04 mbar; 0,04-0,05 mbar; 0,05-0,06 mbar; 0,06-0,07 mbar; 0,07-0,08 mbar; 0,08-0,09 mbar; 0,09-0,10 mbar; 0,1-0,2 mbar; 0,2-0,3 mbar; 0,3-0,4 mbar; 0,4-0,5 mbar; 0,5-0,6 mbar; 0,6-0,7 mbar; 0,7-0,8 mbar; 0,8-0,9 mbar; 0,9-1,0 mbar; 1-2 mbar; 2-3 mbar; 3-4 mbar; 4-5 mbar; 5-6 mbar; 6-7 mbar; 7-8 mbar; 8-9 mbar; 9-10 mbar; 10-20 mbar; 20-30 mbar; 30-40 mbar; 40-50 mbar; 50-60 mbar; 60-70 mbar; 70-80 mbar; 80-90 mbar; und 90-100 mbar.

8. Verfahren nach einem der Ansprüche 1 bis 6, wobei P mindestens ist: 0,01 mbar; 0,02 mbar; 0,03 mbar; 0,04 mbar; 0,05 mbar; 0,06 mbar; 0,07 mbar; 0,08 mbar; 0,09 mbar; 0,1 mbar; 0,2 mbar; 0,3 mbar; 0,4 mbar; 0,5 mbar; 0,6 mbar; 0,7 mbar; 0,8 mbar; 0,9 mbar; 1 mbar; 2 mbar; 3 mbar; 4 mbar; 5 mbar; 6 mbar; 7 mbar; 8 mbar; 9 mbar; 10 mbar; 20 mbar; 30 mbar; 40 mbar; 50 mbar; 60 mbar; 70 mbar; 80 mbar; 90 mbar; oder 100 mbar.

9. Verfahren nach einem vorhergehenden Anspruch, wobei P kleiner ist als: 100 mbar; 90 mbar; 80 mbar; 70 mbar; 60 mbar; 50 mbar; 40 mbar; 30 mbar; 20 mbar; 10 mbar; 9 mbar; 8 mbar; 7 mbar; 6 mbar; 5 mbar; 4 mbar; 3 mbar; 2 mbar; 1 mbar; 0,9 mbar; 0,8 mbar; 0,7 mbar; 0,6 mbar; 0, 5 mbar; 0,4 mbar; 0, 3 mbar; 0, 2 mbar; 0,1 mbar; 0,09 mbar; 0,08 mbar; 0,07 mbar; 0,06 mbar; 0,05 mbar; 0,04 mbar; 0,03 mbar; oder 0,02 mbar.

10. Verfahren nach einem vorhergehenden Anspruch, wobei P ausgewählt ist aus der Gruppe, die besteht aus: (i) > 0,01 mbar; (ii) > 0,05 mbar; (iii) > 0,1 mbar; (iv) > 0,2 mbar; (v) > 0,5 mbar; (vi) > 1 mbar; (vii) > 2 mbar; (viii) > 5 mbar; und (ix) > 10 mbar.

11. Verfahren nach einem vorhergehenden Anspruch, wobei die Probe von Ionen mindestens einige Ionen umfasst, die ähnliche oder im Wesentlichen dieselben Verhältnisse Masse zu Ladung, aber verschiedene Ladungszustände aufweisen.

12. Verfahren nach Anspruch 11, wobei mindestens einige der Ionen, die ähnliche oder im Wesentlichen dieselben Verhältnisse Masse zu Ladung aufweisen, Verhältnisse Masse zu Ladung aufweisen, die sich um weniger als Folgendes unterscheiden: (i) 20 Masse- zu Ladungseinheiten; (ii) 15 Masse- zu Ladungseinheiten; (iii) 10 Masse- zu Ladungseinheiten; (iv) 5 Masse- zu Ladungseinheiten; (v) 4 Masse- zu Ladungseinheiten; (vi) 3 Masse- zu Ladungseinheiten; (vii) 2 Masse- zu Ladungseinheiten; und (viii) 1 Masse- zu Ladungseinheit, wobei 1 Masse- zu Ladungseinheit der Einheit 1 Dalton pro elektronischer Ladungseinheit gleicht.

13. Verfahren nach einem vorhergehenden Anspruch, wobei die Probe von Ionen mehrere ionisierte Moleküle umfasst, wobei die Moleküle mehrere verschiedene Biopolymere, Proteine, Peptide, Polypeptide, Oligonukleotide, Oligonukleoside, Aminosäuren, Kohlenhydrate, Zucker, Lipide, Fettsäuren, Vitamine, Hormone, Abschnitte oder Fragmente von DNA, Abschnitte oder Fragmente von cDNA, Abschnitte oder Fragmente von RNA, Abschnitte oder Fragmente von mRNA, Abschnitte oder Fragmente von tRNA, polyklonale Antikörper, monoklonale Antikörper, Ribonukleasen, Enzyme, Metabolite, Polysaccharide, phosphorisierte Peptide, phosphorisierte Proteine, Glycopeptide, Glycoproteine oder Steroide umfassen

14. Verfahren nach einem vorhergehenden Anspruch, wobei die Ionenführung mittels Wechselspannung oder mittels Hochfrequenz Elektroden umfasst und wobei die Ionenführung mittels Wechselspannung oder mittels Hochfrequenz eine zentrale Längsachse aufweist und wobei die Kombination von Druck und Einfangzeit derart ist, dass einfach geladene Ionen von der zentralen Längsachse radial nach außen gezwungen werden, während mehrfach geladene Ionen in Richtung der zentralen Längsachse gezwungen werden.

15. Verfahren nach einem vorhergehenden Anspruch, wobei die einfach geladenen Ionen im Wesentlichen von der Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz ausgeworfen werden oder verloren gehen.

16. Verfahren nach einem vorhergehenden Anspruch, wobei mindestens einige oder eine Mehrzahl der mehrfach geladenen Ionen im Wesentlichen innerhalb der Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz zurückgehalten werden.

17. Verfahren nach einem der Ansprüche 1 bis 15, wobei eine oder mehrere der folgenden Gruppen von Ionen im Wesentlichen von der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz ausgeworfen werden oder verloren gehen: (i) Ionen mit 2 Ladungen; (ii) Ionen mit 3 Ladungen; (iii) Ionen mit 4 Ladungen; (iv) Ionen mit 5 Ladungen; (v) Ionen mit 6 Ladungen; (vi) Ionen mit 7 Ladungen; (vii) Ionen mit 8 Ladungen; (viii) Ionen mit 9 Ladungen; (ix) Ionen mit 10 Ladungen; (x) Ionen mit 11 Ladungen; (xi) Ionen mit 12 Ladungen; (xii) Ionen mit 13 Ladungen; (xiii) Ionen mit 14 Ladungen; (xiv) Ionen mit 15 Ladungen; (xv) Ionen mit 16 Ladungen; (xvi) Ionen mit 17 Ladungen; (xvii) Ionen mit 18 Ladungen; (xviii) Ionen mit 19 Ladungen; (xix) Ionen mit 20 Ladungen; (xx) Ionen mit 21 Ladungen; (xxi) Ionen mit 22 Ladungen; und (xxii) Ionen mit mehr als 22 Ladungen.

18. Verfahren nach einem der Ansprüche 1 bis 15, wobei eine oder mehrere der folgenden Gruppen von Ionen im Wesentlichen von der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz zurückgehalten werden: (i) Ionen mit 2 Ladungen; (ii) Ionen mit 3 Ladungen; (iii) Ionen mit 4 Ladungen; (iv) Ionen mit 5 Ladungen; (v) Ionen mit 6 Ladungen; (vi) Ionen mit 7 Ladungen; (vii) Ionen mit 8 Ladungen; (viii) Ionen mit 9 Ladungen; (ix) Ionen mit 10 Ladungen; (x) Ionen mit 11 Ladungen; (xi) Ionen mit 12 Ladungen; (xii) Ionen mit 13 Ladungen; (xiii) Ionen mit 14 Ladungen; (xiv) Ionen mit 15 Ladungen; (xv) Ionen mit 16 Ladungen; (xvi) Ionen mit 17 Ladungen; (xvii) Ionen mit 18 Ladungen; (xviii) Ionen mit 19 Ladungen; (xix) Ionen mit 20 Ladungen; (xx) Ionen mit 21 Ladungen; (xxi) Ionen mit 22 Ladungen; und (xxii) Ionen mit mehr als 22 Ladungen.

19. Verfahren nach Anspruch 1, wobei unerwünschte, einfach geladene Hintergrundionen aus einer Mischung von einfach geladenen Hintergrundionen und mehrfach geladenen Analytionen entfernt werden, wobei das Verfahren umfasst:

Übertragen der Mischung von Ionen an die Ionenführung (5) auf der Basis von Wechselspannung oder Hochfrequenz;

Einfangen der Ionen innerhalb der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz, wobei die Ionenführung bei dem Druck P gehalten wird; und Festsetzen einer Zeitdauer T, während derer die Ionen innerhalb der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz gefangen werden, auf einen Wert derart, dass mindestens 50 %, 60 %, 70 %, 80 %, 90 % oder mehr al 90 % der einfach geladenen Ionen im Wesentlichen von der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz ausgeworfen werden oder verloren gehen, während 50 %, 60 %, 70 %, 80 %, 90 % oder mehr al 90 % der mehrfach geladenen Ionen im Wesentlichen innerhalb der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz gehalten werden.

20. Verfahren nach Anspruch 1, das ein Entfernen oder ein (quantitatives) Verdünnen einfach und/oder doppelt geladener Ionen aus einer Mischung von mindestens einfach, doppelt und dreifach geladenen Ionen umfasst.

21. Verfahren nach Anspruch 1, das umfasst:

Bereitstellen einer Probe einfach geladener Ionen und doppelt geladener Ionen, die ähnliche Verhältnisse Masse zu Ladung aufweisen;

fortschreitendes Übertragen der doppelt geladenen Ionen, während mindestens teilweise die einfach geladenen Ionen relativ verdünnt werden; und

Massenanalyse der doppelt geladenen Ionen.

22. Verfahren nach Anspruch 1, das umfasst:

Betreiben der Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz in einer ersten Betriebsart, um im Wesentlichen Ionen, die an einem Eingang zu der Ionenführung empfangen worden sind, hindurch zu einem Ausgang der Ionenführung zu übertragen; und

Betreiben der Ionenführung mittels Wechselspannung oder mittels Hochfrequenz in einer zweiten Betriebsart, wobei die Ionenführung als eine Ionenfalle wirkt, um im Wesentlichen Ionen innerhalb der Ionenführung einzufangen und um im Wesentlichen zu verhindern, dass die Ionen die Ionenführung verlassen, wobei in der zweiten Betriebsart die Ionenführung mittels Wechselspannung oder mittels Hochfrequenz den relativen Anteil oder die relative Häufigkeit von mehrfach geladenen Ionen in der Probe erhöht.

23. Verfahren nach Anspruch 22, wobei die Zeitdauer T eine kontinuierliche oder im Wesentlichen kontinuierliche Zeitdauer ist.

24. Verfahren nach Anspruch 22, wobei die Zeitdauer T eine kumulative Zeitdauer ist.

25. Massenspektrometer, das umfasst:

eine Ionenquelle (1);

eine Vakuumkammer (4), die die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz, die im Gebrauch bei einem Druck P gehalten wird, beherbergt;

eine Elektrode (6), wobei in einer ersten Betriebsart ein Potential an die Elektrode (6) angelegt wird, das ein Probe von Ionen veranlasst, im Wesentlichen innerhalb der Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz gefangen zu sein, und wobei in einer zweiten Betriebsart das Potential an die Elektrode (6) angelegt wird, um Ionen zu ermöglichen, sich aus der Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz zu befreien und zu entweichen;

eine weitere Vakuumkammer (4), die einen Massenanalysator beherbergt; und

wobei das Massenspektrometer dadurch gekennzeichnet ist, dass es außerdem umfasst:

Steuermittel, die angeordnet sind, um den relativen Anteil oder die relative Häufigkeit von mehrfach geladenen Ionen gegenüber einfach geladenen Ionen in der Probe von Ionen zu erhöhen, indem eine Zeitdauer T gesteuert wird, während der die Ionen innerhalb der Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz derart gefangen sind, dass das Produkt P x T mindestens 1 mbar-ms beträgt.

26. Massenspektrometer nach Anspruch 25, das eine Ionenquelle (1) umfasst, um hauptsächlich molekulare oder pseudo-molekulare Ionen zu erzeugen.

27. Massenspektrometer nach Anspruch 25 oder 26, wobei die Ionenquelle (1) eine Ionisationsquelle bei Atmosphärendruck umfasst.

28. Massenspektrometer nach Anspruch 27, wobei die Ionenquelle (1) ausgewählt ist aus der Gruppe, die besteht aus: (i) einer Ionenquelle mittels Elektrospray-Ionisation ("ESI"); (ii) einer Ionenquelle mittels chemischer Ionisation bei Atmosphärendruck ("APCI"); (iii) einer Ionenquelle mittels Photoionisation bei Atmosphärendruck ("APPI"); (iv) einer Ionenquelle mittels einer matrixunterstützten Laser-Desorption/Ionisation ("MALDI") bei Atmosphärendruck; und (v) einer Ionenquelle mittels eines induktiv gekoppelten Plasmas ("ICP").

29. Massenspektrometer nach Anspruch 25 oder 26, wobei die Ionenquelle (1) eine Ionisationsquelle bei Nicht-Atmosphärendruck umfasst.

30. Massenspektrometer nach Anspruch 29, wobei die Ionenquelle (1) ausgewählt ist aus der Gruppe, die besteht aus: (i) einer Ionenquelle mittels eines schnellen Atombombardements ("FAB"); (ii) einer Ionenquelle mittels einer Flüssigkeits-Sekundärionen-Massenspektrometrie ("LSIMS"); (iii) einer Ionenquelle mittels einer matrixunterstützten Laser-Desorption/Ionisation ("MALDI"); (iv) einer Ionenquelle mittels einer matrixunterstützten Laser-Desorption ("MALDI") in Kombination mit einer Kollisionszelle, um durch Kollision Ionen zu kühlen; (v) einer Ionenquelle mittels einer Laser-Desorption/Ionisation ("LDI"); (vi) einer Ionenquelle mittels einer Elektronenstoßionisation ("EI"); und (vii) einer Ionenquelle mittels chemischer Ionisation ("CI").

31. Massenspektrometer nach einem der Ansprüche 25 bis 30, wobei die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz einen Multipolstabsatz umfasst.

32. Massenspektrometer nach Anspruch 31, wobei der Multipolstabsatz einen Quadrupolstabsatz, einen Hexapolstabsatz, einen Oktopolstabsatz oder einen Stabsatz mit zehn oder mehr Stäben umfasst.

33. Massenspektrometer nach einem der Ansprüche 25 bis 30, wobei die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz mehrere Elektroden umfasst, die Öffnungen aufweisen, durch die die Ionen übertragen werden.

34. Massenspektrometer nach Anspruch 33, wobei die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz einen Tunnel mit mehreren Elektroden umfasst, von denen jede im Wesentlichen dieselbe Größe der Öffnung aufweist.

35. Massenspektrometer nach Anspruch 33, wobei die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz einen Ionentrichter umfasst, der mehrere Elektroden aufweist, wobei die Größe der Öffnungen fortschreitend kleiner oder größer wird.

36. Massenspektrometer nach einem der Ansprüche 25 bis 30, wobei die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz eine Doppelhelix-Anordnung von Elektroden umfasst.

37. Massenspektrometer nach einem der Ansprüche 25 bis 30, wobei die Ionenführung (5) mittels Wechselspannung oder mittels Hochfrequenz mehrere Platten umfasst, die benachbart zueinander aufgeschichtet sind.

38. Massenspektrometer nach einem der Ansprüche 25 bis 37, das ferner einen Massenanalysator umfasst.

39. Massenspektrometer nach Anspruch 38, wobei der Massenanalysator ausgewählt ist aus der Gruppe, die besteht aus: (i) einem Flugzeit-Massenanalysator; (ii) einem Quadrupol-Massenanalysator; (iii) einer 2D- oder einer 3D-Ionenfalle; (iv) einem Fouriertransformations-Massenspektrometer; und (v) aus einem Fouriertransformations-Ionenzyklotronresonanz-Massenspektrometer.

40. Massenspektrometer nach einem der Ansprüche 25 bis 39, das ferner eine weitere Ionenführung (8) mittels Wechselspannung oder mittels Hochfrequenz umfasst, die in einer weiteren Vakuumkammer (7) angeordnet ist.

41. Massenspektrometer nach einem der Ansprüche 25 bis 40, das ferner einen Quadrupolmassenfilter und/oder eine Kollisionszelle umfasst, die in noch einer weiteren Vakuumkammer, die dazwischen liegt, angeordnet ist, wobei die Vakuumkammer(n) (4,7) die Ionenführung(en) (5,8) mittels Wechselspannung oder mittels Hochfrequenz beherbergen und wobei die Vakuumkammer den Massenanalysator beherbergt.

42. Massenspektrometer nach Anspruch 40, wobei die weitere Ionenführung (8) mittels Wechselspannung oder mittels Hochfrequenz umfasst: (i) einen Multipolstabsatz; (ii) einen Ionentrichter, der mehrere Elektroden umfasst, die Öffnungen darin aufweisen, durch die Ionen übertragen werden, wobei der Durchmesser der Öffnungen fortschreitend kleiner oder größer wird; (iii) einen Tunnel, der mehrere Elektroden umfasst, die Öffnungen darin aufweisen, durch die Ionen übertragen werden, wobei der Durchmesser der Öffnungen im Wesentlichen konstant bleibt; (iv) eine Doppelhelix-Anordnung von Elektroden; und (v) einen Schichtstapel von Platten, wobei benachbarte Elektroden mit entgegengesetzten Phasen einer Wechselspannungs- oder einer Hochfrequenzversorgung verbunden sind.

Revendications

1. Procédé de spectrométrie de masse comprenant une étape consistant à prendre au piège un échantillon d'ions dans un guide d'ions AC ou RF (5) en présence d'un gaz à une pression P pendant une période de temps T,
ledit procédé étant caractérisé en incluant une étape consistant à améliorer la proportion relative ou l'abondance d'ions multiplement chargés par rapport à des ions simplement chargés dans ledit échantillon d'ions; le produit P x T étant d'au moins 1 mbar-ms.

2. Procédé selon la revendication 1, dans lequel le produit P × T est d'au moins : 2 mbar-ms ; 3 mbar-ms ; .4 mbar-ms ; 5 mbar-ms ; 6 mbar-ms ; 7 mbar-ms ; 8 mbar-ms ; 9 mbar-ms ; 10 mbar-ms ; 15 mbar-ms ; 20 mbar-ms ; 25 mbar-ms ; 30 mbar-ms ; 35 mbar-ms ; 40 mbar-ms ; 45 mbar-ms ; 50 mbar-ms ; 55 mbar-ms ; 60 mbar-ms ; 65 mbar-ms ; 70 mbar-ms ; 75 mbar-ms ; 80 mbar-ms ; 85 mbar-ms ; 90 mbar-ms ; 95 mbar-ms ; 100 mbar-ms ; 110 mbar-ms ; 120 mbar-ms ; 130 mbar-ms ; 140 mbar-ms ; 150 mbar-ms ; 160 mbar-ms ; 170 mbar-ms ; 180 mbar-ms ; 190 mbar-ms ; 200 mbar-ms ; 210 mbar-ms ; 220 mbar-ms ; 230 mbar-ms ; 240 mbar-ms ; 250 mbar-ms ; 260 mbar-ms ; 270 mbar-ms ; 280 mbar-ms ; 290 mbar-ms 300 mbar-ms ; 310 mbar-ms ; 320 mbar-ms ; 330 mbar-ms ; 340 mbar-ms ; 350 mbar-ms ; 360 mbar-ms.; 370 mbar-ms ; 350 mbar-ms ; 390 mbar-ms ; 400 mbar-ms ; 410 mbar-ms ; 420 mbar-ms ; 430 mbar-ms ; 440 mbar-ms ; 450 mbar-ms ; 460 mbar-ms ; 470 mbar-ms ; 480 mbar-ms ; 490 mbar-ms ; 500 mbar-ms ; 550 mbar-ms ; 600 mbar-ms ; 650 mbar-ms ; 700 mbar-ms ; 750 mbar-ms ; 800 mbar-ms ; 850 mbar-ms ; 900 mbar-ms ; 950 mbar-ms ; 1 000 mbar-ms ; 1 100 mbar-ms ; 1 200 mbar-ms ; 1 300 mbar-ms ; 1 400 mbar-ms ; 1 500 mbar-ms ; 1 600 mbar-ms ; 1 700 mbar-ms ; 1 800 mbar-ms ; 1 900 mbar-ms ; 2 000 mbar-ms ; 2 500 mbar-ms ; 3 000 mbar-ms ; 3 500 mbar-ms ; 4 000 mbar-ms ; 4 500 mbar-ms ; 5 000 mbar-ms ; 5 500 mbar-ms ; 6 000 mbar-ms ; 6 500 mbar-ms ; 7 000 mbar-ms ; 7 500 mbar-ms ; 8 000 mbar-ms ; 8 500 mbar-ms ; 9 000 mbar-ms ; 9 500 mbar-ms ; ou 10 000 mbar-ms.

3. Procédé selon la revendication 1 ou 2, dans lequel le produit P × T est inférieur à : 2 mbar-ms ; 3 mbar-ms ; 4 mbar-ms ; 5 mbar-ms ; 6 mbar-ms ; 7 mbar-ms ; 8 mbar-ms ; 9 mbar-ms ; 10 mbar-ms ; 15 mbar-ms ; 20 mbar-ms ; 25 mbar-ms ; 30 mbar-ms ; 35 mbar-ms ; 40 mbar-ms.; 45 mbar-ms ; 50 mbar-ms ; 55 mbar-ms ; 60 mbar-ms ; 65 mbar-ms ; 70 mbar-ms ; 75 mbar-ms ; 80 mbar-ms ; 85 mbar-ms ; 90 mbar-ms ; 95 mbar-ms ; 100 mbar-ms ; 110 mbar-ms ; 120 mbar-ms ; 130 mbar-ms ; 140 mbar-ms ; 150 mbar-ms ; 160 mbar-ms ; 170 mbar-ms ; 180 mbar-ms ; 190 mbar-ms ; 200 mbar-ms ; 210 mbar-ms ; 220 mbar-ms ; 230 mbar-ms ; 240 mbar-ms ; 250 mbar-ms ; 260 mbar-ms ; 270 mbar-ms ; 280 mbar-ms ; 290 mbar-ms ; 300 mbar-ms ; 310 mbar-ms ; 320 mbar-ms ; 330 mbar-ms ; 340 mbar-ms ; 350 mbar-ms ; 360 mbar-ms ; 370 mbar-ms ; 380 mbar-ms ; 390 mbar-ms ; 400 mbar-ms ; 410 mbar-ms ; 420 mbar-ms ; 430 mbar-ms ; 440 mbar-ms ; 450 mbar-ms ; 460 mbar-ms ; 470 mbar-ms ; 480 mbar-ms ; 490 mbar-ms ; 500 mbar-ms ; 550 mbar-ms ; 600 mbar-ms ; 650 mbar-ms ; 700 mbar-ms ; 750 mbar-ms ; 800 mbar-ms ; 850 mbar-ms ; 900 mbar-ms ; 950 mbar-ms ; 1 000 mbar-ms ; 1 100 mbar-ms ; 1 200 mbar-ms ; 1 300 mbar-ms ; 1 400 mbar-ms ; 1 500 mbar-ms ; 1 600 mbar-ms ; 1 700 mbar-ms ; 1 800 mbar-ms ; 1 900 mbar-ms ; 2 000 mbar-ms ; 2 500 mbar-ms ; 3 000 mbar-ms ; 3 500 mbar-ms ; 4 000 mbar-ms ; 4 500 mbar-ms ; 5 000 mbar-ms ; 5 500 mbar-ms ; 6 000 mbar-ms ; 6 500 mbar-ms ; 7 000 mbar-ms ; 7 500 mbar-ms ; 8 000 mbar-ms ; 8 500, mbar-ms ; 9 000 mbar-ms ; 9 500 mbar-ms ; ou 10 000 mbar-ms.

4. Procédé selon la revendication 1, 2 ou 3, dans lequel T tombe à l'intérieur d'une plage sélectionnée à partir du groupe constitué par : 50-100 µs 100-150 µs ; 150-200 µs ; 200-250 µs ; 250-300 µs 300-350 µs ; 350-400 µs ; 400-450 µs ; 450-500 µs 500-550 µs ; 550-600 µs ; 600-650 µs ; 650-700 µs 700-750 µs ; 750-800 µs ; 800-850 µs ; 850-900 µs 900-950 µs ; 950-1 000 µs ; 1-2 ms ; 2-3 ms ; 3-4 ms ; 4-5 ms ; 5-6 ms ; 6-7 ms ; 7-8 ms ; 8-9 ms ; 9-10 ms ; 10-15 ms ; 15-20 ms ; 20-25 ms ; 25-30 ms ; 30-35 ms ; 35-40 ms ; 40-45 ms ; 45-50 ms ; 50-55 ms ; 55-60 ms ; 60-65 ms ; 65-70 ms ; 70-75 ms ; 75-80 ms ; 80-85 ms ; 85-90 ms ; 90-95 ms ; 95-100 ms ; 100-110 ms ; 110-120 ms ; 120-130 ms ; 130-140 ms ; 140-150 ms ; 150-160 ms ; 160-170 ms ; 170-180 ms ; 180-190 ms ; 190-200 ms ; 200-250 ms ; 250-300 ms ; 300-350 ms ; 350-400 ms ; 400-450 ms ; 450-500 ms ; 500-550 ms ; 550-600 ms ; 600-650 ms ; 650-700 ms ; 700-750 ms ; 750-800 ms ; et 950-1 000 ms.

5. Procédé selon la revendication 1, 2 ou 3, dans lequel T est d'au moins : 50 µS ; 60 µs ; 70 µs 80 µs ; 90 µs ; 100 µs ; 200 µs ; 300 µs; 400 µs 500 µs ; 600 µs ; 700 µs ; 800 µs ; 900 µs ; 1000 µs 2 ms ; 3 ms ; 4 ms ; 5 ms ; 6 ms ; 7 ms ; 8 ms ; 9 ms ; 10 ms ; 20 ms ; 30 ms ; 40 ms ; 50 ms ; 60 ms ; 70 ms ; 80 ms ; 90 ms ; 100 ms ; 100 ms ; 200 ms ; 300 ms ; 400 ms ; 500 ms ; 600 ms ; 700 ms ; 800 ms ; 900 ms ; 1 s ; 2 s ; 3 s ; 4 s ; 5 s ; 6 s ; 8 s ; 9 s ; ou 10 s.

6. Procédé selon la revendication 1, 2, 3 ou 5, dans lequel T est inférieur à : 10 s ; 9 s ; 8 s ; 7 s ; 6 s ; 5 s ; 4 s ; 3 s ; 2 s ; 1 000 ms ; 900 ms ; 800 ms ; 700 ms ; 600 ms ; 500 ms ; 400 ms ; 300 ms ; 200 ms ; 100 ms ; 90ms ; 80 ms ; 70 ms ; 60 ms ; 50 ms ; 40 ms ; 30 ms ; 20 ms ; 10 ms ; 9 ms ; 8 ms ; 7 ms ; 6 ms ; 5 ms ; 4 ms ; 3 ms ; 2 ms ; 1 000 µs ; 900 µs ; 800 µs 700 µs ; 600 µs 500 µs ; 400 µs ; 300 µs ; 200 µs ; 100 µs ; 90 µs ; 80 µs 70 µs ; 60 µs ; ou 50 µs.

7. Procédé selon n'importe quelle revendication précédente, dans lequel P tombe dans une plage sélectionnée à partir du groupe constitué par : 0,01-0,02 mbar ; 0,02-0,03 mbar ; 0,03-0,04 mbar ; 0,04-0,05 mbar ; 0,05-0,06 mbar ; 0,06-0,07 mbar ; 0,07-0,08 mbar ; 0,08-0,09 mbar ; 0,09-0,10 mbar ; 0,1-0,2 mbar ; 0,2-0,3 mbar ; 0,3-0,4 mbar ; 0,4-0,5 mbar ; 0,5-0,6 mbar ; 0,6-0,7 mbar ; 0,7-0,8 mbar ; 0,8-0,9 mbar ; 0,9-1,0 mbar ; 1-2 mbar ; 2-3 mbar ; 3-4 mbar ; 4-5 mbar ; 5-6 mbar ; .6-7 mbar ; 7-8 mbar ; 8-9 mbar ; 9-10 mbar ; 10-20 mbar ; 20-30 mbar ; 30-40 mbar ; 40-50 mbar ; 50-60 mbar ; 60-70 mbar ; 70-80 mbar ; 80-90 mbar ; et 90-100 mbar.

8. Procédé selon n'importe laquelle des revendications 1-6, dans lequel P est d'au moins : 0,01 mbar ; 0,02 mbar ; 0,03 mbar ; 0,04 mbar ; 0,05 mbar ; 0,06 mbar ; 0,07 mbar ; 0,08 mbar ; 0,09 mbar ; 0,1 mbar ; 0,2 mbar ; 0,3 mbar ; 0,4 mbar ; 0,5 mbar ; 0,6 mbar; 0,7 mbar ; 0,8 mbar ; 0,9 mbar ; 1 mbar ; 2 mbar ; 3 mbar ; 4 mbar ; 5 mbar ; 6 mbar ; 7 mbar ; 8 mbar ; 9 mbar ; 10 mbar ; 20 mbar ; 30 mbar ; 40 mbar ; 50 mbar-; 60 mbar ; 70 mbar ; 80 mbar ; 90 mbar ; ou 100 mbar.

9. Procédé selon n'importe quelle revendication précédente, dans lequel P est inférieur à : 100 mbar ; 90 mbar ; 80 mbar ; 70 mbar ; 60 mbar ; 50 mbar ; 40 mbar ; 30 mbar ; 20 mbar ; 10 mbar ; 9 mbar ; 8 mbar ; 7 mbar ; 6 mbar.; 5 mbar ; 4, mbar ; 3 mbar ; 2 mbar ; 1 mbar ; 0,9 mbar ; 0,8 mbar ; 0,7 mbar ; 0,6 mbar ; 0,5 mbar ; 0,4 mbar ; 0,3 mbar ; 0,2 mbar ; 0,10 mbar ; 0,09 mbar ; 0,08 mbar ; 0,07 mbar ; 0,06 mbar ; 0,05 mbar ; 0,04 mbar ; 0,03 mbar ; ou 0,02 mbar.

10. Procédé selon n'importe quelle revendication précédente, dans lequel P est sélectionné à partir du groupe constitué par : (i) > 0,01 mbar ; (ii) > 0,05 mbar ; (iii) > 0,1 mbar ; (iv) > 0,2 mbar ; (v) > 0,5 mbar ; (vi) > 1 mbar ; (vii) > 2 mbar ; (viii) > 5 mbar ; et (ix) > 10 mbar.

11. Procédé selon n'importe quelle revendication précédente, dans lequel ledit échantillon d'ions comprend au moins quelques ions ayant des rapports masse sur charge similaires ou sensiblement identiques, mais des états de charge différents.

12. Procédé selon la revendication 11, dans lequel lesdits au moins quelques ions ayant des rapports masse sur charge similaires ou sensiblement identiques ont des rapports masse sur charge qui diffèrent de moins de : (i) 20 unités de masse sur charge ; (ii) 15 unités de masse sur charge ; (iii) 10 unités de masse sur charge ; (iv) 5 unités de masse sur charge ; (v) 4 unités de masse sur charge ; (vi) 3 unités de masse sur charge ; (vii) 2 unités de masse sur charge ; et (viii) 1 unité de masse sur charge, dans lequel 1 unité de masse sur charge est égale à 1 dalton par unité de charge électronique.

13. Procédé selon n'importe quelle revendication précédente, dans lequel ledit échantillon d'ions comprend une pluralité de molécules ionisées, lesdites molécules comprenant une pluralité de différents biopolymères, protéines, peptides, polypeptides, oligonucléotides, oligonucléosides, acides aminés, hydrates de carbone, sucres, lipides, acides gras, vitamines, hormones, parties ou fragments d'ADN, parties ou fragments d'ADNc, parties ou fragments d'ARN, parties ou fragments d'ARNm, parties ou fragments d'ARNt, anticorps polyclonaux, anticorps monoclonaux, ribonucléases, enzymes, métabolites, polysaccharides, peptides phosphorylés, protéines phosphorylées, glycopeptides, glycoprotéines ou stéroïdes.

14. Procédé selon n'importe quelle revendication précédente, dans lequel le guide d'ions AC ou RF comprend des électrodes et le guide d'ion AC ou RF a un axe longitudinal central, et dans lequel la combinaison de pression et de temps de prise au piège est telle que des ions simplement chargés sont forcés de façon radiale à l'extérieur dudit axe longitudinal central tandis que des ions multiplement chargés sont forcés vers ledit axe longitudinal central.

15. Procédé selon n'importe quelle revendication précédente, dans lequel lesdits ions simplement chargés sont sensiblement éjectés de ou perdus dudit guide d'ions AC ou RF (5).

16. Procédé selon n'importe quelle revendication précédente, dans lequel au moins certains ou une majorité desdits ions multiplement chargés sont sensiblement retenus à l'intérieur dudit guide d'ions AC ou RF (5).

17. Procédé selon n'importe laquelle des revendications 1 à 15, dans lequel un ou plusieurs des groupes suivants d'ions sont sensiblement éjectés ou perdus dudit guide d'ions AC ou RF : (i) ions ayant 2 charges ; (ii) ions ayant 3 charges ; (iii) ions ayant 4 charges ; (iv) ions ayant 5 charges ; (v) ions ayant 6 charges ; (vi) ions ayant 7 charges ; (vii) ions ayant 8 charges ; (viii) ions ayant 9 charges ; (ix) ions ayant 10 charges ; (x) ions ayant 11 charges ; (xi) ions ayant 12 charges ; (xii) ions ayant 13 charges ; (xiii) ions ayant 14 charges ; (xiv) ions ayant 15 charges ; (xv) ions ayant 16 charges ; (xvi) ions ayant 17 charges ; (xvii) ions ayant 18 charges ; (xviii) ions ayant 19 charges ; (xix) ions ayant 20 charges ; (xx) ions ayant 21 charges ; (xxi) ions ayant 22 charges ; et (xxii) ions ayant plus de 22 charges.

18. Procédé selon n'importe laquelle des revendications 1 à 15, dans lequel un ou plusieurs des groupes suivants d'ions sont sensiblement retenus avec ledit guide d'ions AC ou RF : (i) ions ayant 2 charges ; (ii) ions ayant 3 charges ; (iii) ions ayant 4 charges ; (iv) ions ayant 5 charges ; (v) ions ayant 6 charges ; (vi) ions ayant 7 charges ; (vii) ions ayant 8 charges ; (viii) ions ayant 9 charges ; (ix) ions ayant 10 charges ; (x) ions ayant 11 charges ; (xi). ions ayant 12 charges ; (xii) ions ayant 13 charges ; (xiii) ions ayant 14 charges ; (xiv) ions ayant 15 charges ; (xv) ions ayant 16 charges ; (xvi) ions ayant 17 charges ; (xvii) ions ayant 18 charges ; (xviii) ions ayant 19 charges ; (xix) ions ayant 20 charges ; (xx) ions ayant 21 charges ; (xxi) ions ayant 22 charges ; et (xxii) ions ayant plus de 22 charges.

19. Procédé selon la revendication 1, dans lequel des ions de fond indésirables simplement chargés sont enlevés d'un mélange d'ions de fond simplement chargés et d'ions de substance à analyser multiplement chargés, ledit procédé comprenant :

la transmission dudit mélange d'ions audit guide d'ion AC ou RF (5) ;

la prise au piège desdits ions à l'intérieur dudit guide d'ions AC ou RF maintenu à ladite pression P ; et

la fixation de ladite période de temps T pendant laquelle les ions sont pris au piège à l'intérieur du guide d'ions AC ou RF à une valeur telle qu'au moins 50 %, 60 %, 70 %, 80 %, 90 % ou plus de 90 % desdits ions simplement chargés seront sensiblement éjectés ou perdus du guide d'ions AC ou RF tandis qu'au moins 50 %, 60 %, 70 %, 80 %, 90 % ou plus de 90 % desdits ions multiplement chargés seront sensiblement maintenus dans ledit guide d'ions AC ou RF.

20. Procédé selon la revendication 1, comprenant l'enlèvement ou l'atténuation d'ions simplement et/ou doublement chargés d'un mélange d'ions au moins simplement, doublement et triplement chargés.

21. Procédé selon la revendication 1 comprenant :

la fourniture d'un échantillon d'ions simplement chargés et d'ions doublement chargés ayant des rapports masse sur charge similaires ;

la transmission incessante desdits ions doublement chargés pendant l'atténuation au moins relativement partiellement desdits ions simplement chargés ; et

l'analyse de masse desdits ions doublement chargés.

22. Procédé selon la revendication 1 comprenant :

la mise en oeuvre dudit guide d'ions AC ou RF (5) dans un premier mode pour sensiblement transmettre des ions reçus au niveau d'une entrée au guide d'ions par l'intermédiaire d'une sortie du guide d'ions ; et

la mise en oeuvre dudit guide d'ions AC ou RF dans un second mode dans lequel ledit guide d'ions agit comme un piège à ions pour sensiblement prendre au piège des ions à l'intérieur dudit guide d'ions et pour sensiblement empêcher lesdits ions de quitter le guide d'ions, dans lequel dans ledit second mode le guide d'ions AC ou RF améliore la proportion relative ou l'abondance d'ions multiplement chargés dans l'échantillon.

23. Procédé selon la revendication 22, dans lequel ladite période de temps T est une période de temps continue ou sensiblement continue.

24. Procédé selon la revendication 22, dans lequel ladite période de temps T est une période de temps cumulée.

25. Spectromètre de masse comprenant :

une source d'ions (1) ;

une chambre à vide (4) logeant un guide d'ions AC ou RF (5) maintenu en fonctionnement à une pression P ;

une électrode (6), dans laquelle dans un premier mode de fonctionnement un potentiel appliqué à ladite électrode (6) amène un échantillon d'ions à être sensiblement pris au piège à l'intérieur dudit guide d'ions AC ou RF (5) et dans lequel dans un second mode de fonctionnement le potentiel appliqué à ladite électrode (6) permet aux ions d'être libérée dudit guide d'ions AC ou RF (5) ;

une chambre à vide supplémentaire logeant un analyseur de masse ; et

ledit spectromètre de masse est caractérisé en ce qu'il comprend également :

un moyen de commande agencé pour améliorer la proportion relative ou l'abondance d'ions multiplement chargés par rapport aux ions simplement chargés dans ledit échantillon d'ions en commandant une période de temps T pendant laquelle des ions sont pris au piège à l'intérieur dudit guide d'ions AC ou RF (5) de sorte que le produit P x T est d'au moins 1 mbar-ms.

26. Spectromètre de masse selon la revendication 25, comprenant une source d'ions (1) pour produire des ions principalement moléculaires ou pseudo-moléculaires.

27. Spectromètre de masse selon la revendication 25 ou 26, dans lequel ladite source d'ions (1) comprend une source d'ionisation à pression atmosphérique.

28. Spectromètre de masse selon la revendication 27, dans lequel ladite source d'ions (1) est sélectionnée à partir du groupe comprenant : (i) une source d'ions par ionisation d'Électronébulisation (« ESI ») ; (ii) une source d'ions par Ionisation Chimique à Pression Atmosphérique (« APCI ») ; (iii) une source d'ions par Photo Ionisation à Pression Atmosphérique (« APPI ») ; (iv) une source d'ions par Désorption-Ionisation Laser Assistée par Matrice à pression atmosphérique (« MALDI ») ; et (v) une source d'ions à Plasma Couplé par Induction (« ICP »).

29. Spectromètre de masse selon la revendication 25 ou 26, dans lequel ladite source d'ions (1) comprend une source d'ionisation à pression non atmosphérique.

30. Spectromètre de masse selon la revendication 29, dans lequel ladite source d'ions (1) est sélectionnée à partir du groupe constitué par : (i) une source d'ions à Bombardement Atomique Rapide (« FAB ») ; (ii) une source d'ions pour Spectrométrie de Masse à Ions Secondaires en phase Liquide. (« LSIMS ») ; (iii) une source d'ions par Désorption-Ionisation Laser Assistée par Matrice (« MALDI ») ; (iv) une source d'ions par Désorption Laser Assistée par Matrice (« MALDI ») en combinaison avec une cellule de collision pour refroidir des ions par collision ; (v) une source d'ions par Désorption-Ionisation Laser (« LDI ») ; (vi) une source d'ions par Impact Électronique (« EI ») ; et (vii) une source d'ions par Ionisation Chimique (« Cl »).

31. Spectromètre de masse selon n'importe laquelle des revendications 25 à 30, dans lequel ledit guide d'ions AC ou RF (5) comprend un ensemble formant tige multipôle.

32. Spectromètre de masse selon la revendication 31, dans lequel ledit ensemble formant tige multipôle comprend un ensemble formant tige quadripôle, un ensemble formant tige hexapôle, un ensemble formant tige octopôle ou un ensemble formant tige ayant dix tiges ou plus.

33. Spectromètre de masse selon n'importe laquelle des revendications 25 à 30, dans lequel ledit guide d'ions AC ou RF (5) comprend une pluralité d'électrodes ayant des ouvertures à travers lesquelles lesdits ions sont transmis.

34. Spectromètre de masse selon la revendication 33, dans lequel ledit guide d'ions AC ou RF (5) comprend un tunnel à ions ayant une pluralité d'électrodes chacune ayant une ouverture sensiblement de la même taille.

35. Spectromètre de masse selon la revendication 33, dans lequel ledit guide d'ions AC ou RF (5) comprend un entonnoir à ions ayant une pluralité d'électrodes dans lesquelles la taille des ouvertures devient progressivement plus petite ou plus grande.

36. Spectromètre de masse selon n'importe laquelle des revendications 25 à 30, dans lequel ledit guide d'ions AC ou RF (5) comprend un agencement d'électrodes en hélice double.

37. Spectromètre de masse selon n'importe laquelle des revendications 25 à 30, dans lequel ledit guide d'ions AC ou RF (5) comprend une pluralité de plaques empilées adjacentes les unes aux autres.

38. Spectromètre de masse selon n'importe laquelle des revendications 25 à 37, comprenant en outre un analyseur de masse.

39. Spectromètre de masse selon la revendication 38, dans lequel ledit analyseur de masse est sélectionné à partir du groupe constitué par : (i) un analyseur de masse à Temps de Vol ; (ii) un analyseur de masse à quadripôle ; (iii) un piège à ions 2D ou 3D ; (iv) un spectromètre de masse à Transformée de Fourier ; et (v) un spectromètre de masse à Résonance Cyclotonique Ionique et Transformée de Fourier.

40. Spectromètre de masse selon n'importe laquelle des revendications 25 à 39, comprenant en outre un guide d'ions AC ou RF supplémentaire (8) agencé dans une chambre à vide supplémentaire (7).

41. Spectromètre de masse selon n'importe laquelle des revendications 25 à 40, comprenant en outre un filtre de masse à quadripôle et/ou une cellule de collision agencée dans une chambre à vide encore supplémentaire intermédiaire aux chambre(s) à vide (4, 7) logeant lesdits guide(s) d'ion AC ou RF (5, 8) et la chambre à vide logeant l'analyseur de masse.

42. Spectromètre de masse selon la revendication 40, dans lequel ledit guide d'ions AC ou RF supplémentaire (8) comprend : (i) un ensemble formant tige multipôle ; (ii) un entonnoir à ions comprenant une pluralité d'électrodes ayant des ouvertures en leur sein à travers lesquelles les ions sont transmis, dans lesquelles le diamètre desdits ouvertures devient progressivement plus petit ou plus grand ; (iii) un tunnel à ions comprenant une pluralité d'électrodes ayant des ouvertures en leur sein à travers lesquelles les ions sont transmis, dans lesquelles le diamètre desdites ouvertures reste sensiblement constant ; (iv) un agencement en hélice double d'électrodes ; et (v) un empilement de plaques dans lequel des électrodes adjacentes sont reliées à des phases opposées d'une alimentation RF ou AC.

Drawing