Mass spectrometer

Patent metadata

Field	Value
Publication number	US-9679752-B2
Application number	US-99623606-A
Country	US
Kind code	B2
Filing date	Jul 21, 2006
Priority date	Jul 21, 2005
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A mass spectrometer is disclosed comprising a mass selective ion trap ( 12 ) and a quadrupole rod set mass filter ( 14 ) arranged downstream of the mass selective ion trap ( 12 ). Ions are mass selectively ejected from the ion trap ( 12 ) in a substantially synchronized manner with the scanning of the mass filter ( 14 ) in order to increase the duty cycle of the mass filter ( 14 ).

First claim

The invention claimed is:

1. A mass spectrometer comprising:
a mass or mass to charge ratio selective ion trap comprising a plurality of electrodes;
a first mass filter arranged downstream of said mass or mass to charge ratio selective ion trap;
control means configured to:
(i) cause a first population of ions to be trapped and accumulated for a first period of time;
(ii) cause a second population of ions to be trapped and accumulated for a second period of time in said ion trap whilst causing said first population of ions to be selectively ejected or released from said ion trap exclusively according to their mass or mass to charge ratio, wherein said first period of time is substantially equal to said second period of time and the scan time of said first mass filter;
(iii) after said second period of time, transfer said second population of ions to a downstream portion of said ion trap; and
(iv) scan said first mass filter in a substantially synchronised manner with the selective ejection or release of ions from said ion trap.

2. A mass spectrometer as claimed in claim 1 , wherein said first mass filter comprises a quadrupole rod set mass filter.

3. A mass spectrometer as claimed in claim 1 , wherein the mass or mass to charge ratio resolution of said first mass filter is greater than the mass or mass to charge ratio resolution of said ion trap.

4. A mass spectrometer as claimed in claim 1 , wherein said control means is arranged and adapted to cause ions to be sequentially or progressively ejected or released from said ion trap according to their mass or mass to charge ratio.

5. A mass spectrometer as claimed in claim 1 , wherein said control means is arranged and adapted to:
(a) scan said first mass filter in a substantially continuous or linear or progressive or regular manner; or
(b) scan said first mass filter in a substantially non-continuous or stepped or non-linear or non-progressive or irregular manner.

6. A mass spectrometer as claimed in claim 1 , wherein said control means is arranged and adapted to synchronise the selective ejection or release of ions from said ion trap with the scanning of a mass or mass to charge ratio transmission window of said first mass filter.

7. A mass spectrometer as claimed in claim 1 , wherein said ion trap is arranged in a mode of operation to release ions having a first range of mass to charge ratios whilst substantially retaining ions within said ion trap which have mass to charge ratios outside said first range.

8. A mass spectrometer as claimed in claim 1 , further comprising AC or RF voltage means arranged and adapted to apply an AC or RF voltage to at least some of said plurality of electrodes in order to confine radially at least some ions within said ion trap.

9. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises means for confining ions radially within said ion trap.

10. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises means for generating a plurality of axial pseudo-potential wells having a periodicity.

11. A mass spectrometer as claimed in claim 10 , wherein the amplitude of said axial pseudo-potential wells is dependent upon the mass to charge ratio of an ion.

12. A mass spectrometer as claimed in claim 1 , further comprising means for applying an axial electric field along at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of the axial length of said ion trap.

13. A mass spectrometer as claimed in claim 1 , further comprising means for varying or scanning a plurality of axial pseudo-potential wells created along the axial length of said ion trap.

14. A mass spectrometer as claimed in claim 1 , further comprising means for varying an effective potential so as to allow ions of a predetermined mass to charge ratio to be selectively extracted from said ion trap.

15. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises first means arranged and adapted to maintain one or more DC, real or static potential wells or a substantially static inhomogeneous electric field along at least a portion of the axial length of said ion trap in a first mode of operation.

16. A mass spectrometer as claimed in claim 15 , wherein said ion trap comprises second means arranged and adapted to maintain a time varying substantially homogeneous axial electric field along at least a portion of the axial length of said ion trap in said first mode of operation.

17. A mass spectrometer as claimed in claim 15 , wherein said ion trap comprises ejection means arranged and adapted in a mode of operation to eject at least some ions from a trapping region of said ion trap in a substantially non-resonant manner whilst other ions are arranged to remain substantially trapped within said trapping region of said ion trap.

18. A mass spectrometer as claimed in claim 17 , wherein said ejection means is arranged and adapted in said first mode of operation to eject ions substantially axially from said ion trap.

19. A mass spectrometer as claimed in claim 1 , further comprising ejection means arranged and adapted to mass or mass to charge ratio selectively eject ions from said ion trap.

20. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises a linear ion trap.

21. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises a multipole rod set ion trap.

22. A mass spectrometer as claimed in claim 1 , wherein said ion trap is segmented axially or comprises a plurality of axial segments.

23. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises a plurality of electrodes having apertures wherein ions are transmitted, in use, through said apertures.

24. A mass spectrometer as claimed in claim 1 , wherein said ion trap comprises a plurality of axial segments.

25. A mass spectrometer as claimed in claim 1 , further comprising means arranged and adapted to apply one or more transient DC voltages or one or more transient DC voltage waveforms to said plurality of electrodes initially at a first axial position, wherein said one or more transient DC voltages or one or more transient DC voltage waveforms are then subsequently provided at second, then third different axial positions along said ion trap.

26. A mass spectrometer as claimed in claim 25 , wherein said one or more transient DC voltages create: (i) a potential hill or barrier; (ii) a potential well; (iii) multiple potential hills or barriers; (iv) multiple potential wells; (v) a combination of a potential hill or barrier and a potential well; or (vi) a combination of multiple potential hills or barriers and multiple potential wells.

27. A mass spectrometer as claimed in claim 25 , wherein said one or more transient DC voltage waveforms comprise a repeating waveform or square wave.

28. A mass spectrometer as claimed in claim 1 , further comprising means arranged and adapted to apply, move or translate one or more transient DC voltages or one or more transient DC voltage waveforms from one end of said ion trap to another end of said ion trap in order to urge ions along at least a portion of the axial length of said ion trap.

29. A mass spectrometer as claimed in claim 1 , further comprising means arranged to apply one or more trapping electrostatic or DC potentials at a first end or a second end

Assignees

• Hoyes John
• Micromass Ltd

Inventors

• Hoyes John

Classifications

• H01J49/429

  Scanning an electric parameter, e.g. voltage amplitude or frequency · CPC title

• H01J49/004 Primary

  Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn · CPC title

• C08L23/04

  Homopolymers or copolymers of ethene · CPC title

• H01J49/422

  Two-dimensional RF ion traps (ion guides without mass selection H01J49/062) · CPC title

• H01J49/4215

  Quadrupole mass filters (H01J49/4225 takes precedence) · CPC title