Multi detector mass spectrometer and spectrometry method filter
地域：
Bremen
摘要
The present invention can be directed to a mass spectrometer, relevant parts thereof like replacement kits or upgrading kits and/or mass spectrometry methods. A mass spectrometer according to the present invention can comprise at least one ion source for generating a beam of ions from a sample. Moreover at least one mass filter downstream of the ion source can be provided and adapted to select ions from the beam by their mass-to-charge ratio (m/z). Furthermore at least one collision cell arranged downstream of the mass filter can be arranged. At least one sector field mass analyser arranged downstream of the collision cell can be further provided and at least one ion multicollector comprising a plurality of ion detectors arranged downstream of the mass analyser, for detecting a plurality of different ion species in parallel and/or simultaneously.
說(shuō)明書
The invention relates to mass spectrometry. The invention furthermore relates to Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and collision cell technology.
In order to achieve high precision and accurate isotope ratio measurements extended physical and chemical sample preparation is applied to get clean samples free from possible interferences and contaminations in the mass spectrum. Typical concentrations of analyte in the sample material can be in the range of parts per billion in the analyte of interest and may be concentrated in small inclusions or crystals within a heterogeneous sample material.
Extended quality control steps are integrated into the sample preparation to ensure that the sample preparation itself does not lead to changes in the isotope ratio of the sample material. Every sample preparation step comes along with the possibility of adding contamination to the samples and isotopic fractionation of the analyte to be extracted from the original sample material, which could be for instance a rock, a crystal, soil, a dust particle, a liquid and/or organic matter. Even if all these steps are taken with great care there still is the chance of contamination and incomplete separation and interferences in the mass spectrum.
權(quán)利要求
The invention claimed is:1. A mass spectrometer for determining isotope ratios comprising(a) at least one ion source for generating a beam of elemental ions from a sample; (b) at least one mass filter downstream of the ion source operable to select ions from the beam by their mass-to-charge ratio (m/z) and to transmit only ions having mass within a mass window of at most 30 amu; (c) at least one collision cell arranged downstream of the mass filter and adapted for inducing mass shift reactions to a higher mass within the collision cell for a plurality of target ion species; (d) at least one sector field mass analyser, arranged downstream of the collision cell; and (e) at least one ion multicollector comprising a plurality of ion detectors arranged downstream of the mass analyser, for detecting the plurality of target ion species in parallel and/or simultaneously and determining isotope ratios, the ion species including different isotopes of the same element. 2. The mass spectrometer according to claim 1 wherein the ion source comprises an inductively coupled plasma ion source (ICP). 3. The mass spectrometer according to claim 1 further comprising a laser ablation cell for direct laser ablation of a sample, the laser ablation cell being arranged upstream of the ion source. 4. The mass spectrometer according to claim 1 , wherein the collision cell contains at least one gas inlet for supplying at least one collision gas or reaction gas, so as to facilitate mass shift reactions and/or reduce the absolute kinetic energy and reduce the energy spread of the ions in the ion beam. 5. The mass spectrometer according to claim 1 wherein the mass filter comprises a quadrupole filter, an RF-only driven pre-filter section arranged upstream of the quadrupole filter and/or RF-only driven post-filter section arranged downstream of the quadrupole filter. 6. The mass spectrometer according to claim 5 wherein the quadrupole filter is adapted to be operable in a full mass transmission mode. 7. The mass spectrometer according to claim 5 wherein the pre-filter section and/or the post-filter section is adapted to be set to enhance control of the ion beam phase volume at the entrance of and/or within the quadrupole filter and/or to enhance transmission of the ion beam further downstream. 8. The mass spectrometer according to claim 1 wherein the at least one mass analyser comprises double focusing ion optics for simultaneously analysing a plurality of ion species. 9. The mass spectrometer according to claim 1 wherein the ion multicollector comprises at least one Faraday cup and/or at least one ion counter. 10. The mass spectrometer according to claim 1 wherein the ion multicollector comprises at least 3 Faraday cups and/or 2 ion counters. 11. The mass spectrometer according to claim 9 wherein the multicollector comprises at least one axial channel that comprises at least one switchable collector channel behind a detector slit for switching between a Faraday cup and an ion counter. 12. The mass spectrometer according to claim 1 wherein the mass filter is adapted to be operable to transmit mass within a predefined mass window. 13. The mass spectrometer according to claim 1 wherein the mass filter is adapted to be operable to transmit only ions having a mass within a mass window around a predefined mass, wherein the mass window has a width of at most 30%. 14. The mass spectrometer according to claim 1 wherein the mass filter is adapted to be operable to transmit only ions having a mass within a mass window around a predefined mass, wherein the width of the mass window is selected based on the ion mass range transmitted by the mass analyser to the multicollector. 15. The mass spectrometer according to claim 1 wherein the mass filter is adapted to be operable to (i) transmit only ions having a mass within a first mass window during a first time period in which the mass analyser is set to transmit ions of a first analysis mass range to the multicollector, the first mass window being selected based on the first analysis mass range, and (ii) transmit only ions having a mass within a second mass window during a second time period, following the first time period, in which the mass analyser is set to transmit ions of a second analysis mass range to the multicollector, the second mass window being selected based on the second analysis mass range, wherein the second analysis mass range is different to the first analysis mass range. 16. The mass spectrometer according to claim 1 , wherein the quadrupole mass filter is adapted to transmit a single mass with a mass window of at most 0.9 amu. 17. The mass spectrometer according to claim 1 further comprising a filter for removing non-ionic species that is arranged upstream from the mass filter. 18. The mass spectrometer according to claim 1 further comprising at least one source of gas and at least one inlet of gas. 19. Kit for a multi-detector mass spectrometer, particularly according to claim 1 , comprising at least one mass filter to select ions from an ion beam by their mass-to-charge ratio (m/z), the mass filter being adapted to be arranged downstream of the ion source, being further adapted to be arranged upstream of at least one collision cell and at least one sector field mass analyser, arranged downstream of the collision cell and at least one ion multicollector comprising a plurality of ion detectors arranged downstream of the mass analyser, for detecting a plurality of different ion species in parallel and/or simultaneously. 20. A method of analysing the composition of at least one sample and determining at least one elemental ratio comprising:(a) generating a beam of elemental ions from a sample in an ion source; (b) selecting ions of the ion beam by at least one mass filter downstream of the ion source operable to selectively transmit only ions with mass to charge ratio (m/z) in a pre-determined range within a mass window of at most 30 amu; (c) transmitting the selected ions through at least one collision cell downstream of the mass filter wherein the target ions are mass-shifted and cooled to reduce spread of their kinetic energy; (d) separating the ions transmitted from the collision cell in a sector field analyser based on their mass to charge ratio; (e) detecting the target ions in a multicollector in parallel and/or simultaneously; and (f) determining and/or measuring isotope ratios of isotopes contained in the sample. 21. The method according to claim 20 wherein the ions are generated by an inductively coupled plasma ion source (ICP). 22. The method according to claim 20 wherein analysing the composition comprises determining an isotopic ratio in the sample. 23. The method according to claim 20 further comprising preparing the sample from a geological, geochemical and/or biogeochemical resource before step (a) and a step of determining and/or measuring of isotope ratios of isotopes contained in the sample after step (e). 24. The method according to claim 20 further comprising preparing the sample from a cosmological and/or cosmochemical resource before step (a). 25. The method according to claim 20 further comprising preparing the sample from a life science resource before step (a) and a step of determining and/or measuring isotope ratios of isotopes contained in the sample after step (e). 26. The method according to claim 20 wherein before step (a) a sample is provided and then ablated by laser. 27. The method according to claim 20 , further comprising delivering at least one gas into the collision cell, for cooling down the ion beam in the collision cell, and at least one second gas, for inducing mass shift reactions in the collision cell. 28. The method according to claim 27 comprising a step of delivering He as a major gas into the collision cell. 29. The method according to claim 20 wherein the mass filter is operated (i) to transmit only ions having a mass within a first mass window during a first time period in which the mass analyser is set to transmit ions of a first analysis mass range to the multicollector, the first mass window being selected based on the first analysis mass range, and (ii) to transmit only ions having a mass within a second mass window during a second time period, following the first time period, in which the mass analyser is set to transmit ions of a second analysis mass range to the multicollector, the second mass window being selected based on the second analysis mass range, wherein the second analysis mass range is different to the first analysis mass range. 30. The method according to claim 20 wherein the mass filter is operated to mass select the ion beam to transmit only ions within a pre-determined mass range and the collision cell is provided with a reaction gas to react with at least one ion of interest in the mass selected ion beam thereby producing a mass-shifted ion of interest that lies outside the pre-determined mass range selected by the mass filter.
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