Collision cell for tandem mass spectrometry

Patent metadata

Field	Value
Publication number	US-9685309-B2
Application number	US-201514863384-A
Country	US
Kind code	B2
Filing date	Sep 23, 2015
Priority date	Dec 22, 2011
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

A method and apparatus for tandem mass spectrometry is disclosed. Precursor ions are fragmented and the fragments are accumulated in parallel, by converting an incoming stream of ions from an ion source ( 10 ) into a time separated sequence of multiple precursor ions which are then assigned to their own particular channel of a multi compartment collision cell ( 40 ). In this manner, precursor ion species, being allocated to their own dedicated fragmentation cell chambers ( 41, 42 . . . 43 ) within the fragmentation cell ( 40 ), can then be captured and fragmented by that dedicated fragmentation chamber at optimum energy and/or fragmentation conditions.

First claim

The invention claimed is:

1. A mass spectrometry method, comprising:
generating ions to be analysed;
separating the generated ions into a sequence of ions separated in time in accordance with their mass to charge ratio;
directing ions of a mass to charge ratio M i at an arrival time t i into an i th one of a plurality of N spatially separated parallel cell chambers within a fragmentation cell;
directing ions of a mass to charge ratio M j , different from M i , at an arrival time t j , into a j th one of the plurality of N spatially separated parallel cell chambers;
ejecting ions from each of the cell chambers to a mass analyser; and
analysing ions from each cell chamber in the mass analyser;
wherein ions of at least two different mass to charge ratios M i , M j are stored in respective ones of the spatially separated parallel cell chambers at partially overlapping times; and
wherein an analysis duration for analysing ions in the mass analyser is greater than a difference in arrival times t j −t i for adjacent ions.

2. The method of claim 1 , wherein M i and M j each consist of a mass to charge ratio of a single ion species.

3. The method of claim 1 , wherein Mi and M j each consist of a range of mass to charge ratios.

4. The method of claim 1 , where at least one of ions of mass to charge ratios M i and M j is or are fragmented in the corresponding cell chamber.

5. The method of claim 1 , wherein the step of ejecting ions comprises:
(a) in a first cycle ejecting ions of mass M N from an N th one of the cell chambers to the mass analyser;
(b) in a subsequent cycle, once the N th chamber is empty transferring ions of mass M (N-1) from an (N−1) th chamber to the N th cell chamber;
(c) in a further subsequent cycle ejecting the ions of mass M (N-1) , now in the N th cell chamber, to the mass analyser.

6. The method of claim 5 , further comprising:
trapping ions ejected from the N th chamber in an RF storage device, and ejecting them orthogonally towards the mass analyser.

7. The method of claim 1 , wherein the step of ejecting ions to the mass analyser comprises:
ejecting ions from each of the N cell chambers in a direction that is not towards any other cell chamber such that the ions from each chamber arrive at the mass analyser without first passing through any of the other chambers.

8. The method of claim 7 , further comprising applying a pulsed voltage to the ion deflector to direct the ions to respective cell chambers.

9. The method of claim 1 , further comprising employing an ion deflector to direct ions of the mass M i into the i th one of the cell chambers and to direct ions of the mass M j into the j th one of the cell chambers.

10. The method of claim 1 , further comprising adjusting the energy of the ions prior to entry into the cell chambers.

11. A mass spectrometer; comprising:
an ion source for generating ions from a sample;
an ion separator for separating the generated ions into a sequence of ions separated in time in accordance with their mass to charge ratio and for ejecting the separated ions;
a rastering device positioned to receive the separated ions ejected by the ion separator;
a fragmentation cell including a plurality N of spatially separated parallel cell chambers;
a mass analyser positioned to receive ions from the cell; and
a controller configured to control the rastering device to direct ions of a mass to charge ratio M i received by the rastering device at an arrival time t i into an i th one of the plurality of N spatially separated parallel cell chambers, and to direct ions of a mass to charge ratio M j , different from M i at an arrival time t j , into a j th one of the plurality of N spatially separated parallel cell chambers;
the controller being further configured to cause ions from each of the cell chambers to be ejected to the mass analyser;
wherein the controller is configured to cause ions of at least two different mass to charge ratios M i , M j to be stored in respective ones of the spatially separated parallel cell chambers at partially overlapping times; and
wherein an analysis duration for analysing ions in the mass analyser is greater than a difference in arrival times t j −t i for adjacent ions.

12. The mass spectrometer of claim 11 wherein the cell further comprises a plurality N, of ion entrance apertures, each in communication with the ion entrance of a respective cell chamber.

13. The mass spectrometer of claim 11 wherein each chamber comprises an RF only multipole.

14. The mass spectrometer of claim 11 , further comprising a linear trap positioned to receive ions ejected from each cell chamber, and configured to orthogonally eject ions toward the mass analyser.

15. The mass spectrometer of claim 11 , wherein the ion separator comprises an ion trap.

16. The mass spectrometer of claim 11 , wherein the mass analyser comprises
one of an orbital trapping analyser or a time of flight analyser.

17. The mass spectrometer of claim 11 , wherein the rastering device comprises an ion deflector including first and second deflector plates, and further wherein the controller is arranged to cause pulsed voltages to be applied to those deflector plates.

Assignees

• Thermo Fisher Scient (Bremen) Gmbh

Inventors

• Makarov Alexander Alekseevich

Classifications

• H01J49/0045 Primary

  characterised by the fragmentation or other specific reaction · CPC title

• H01J49/009

  Spectrometers having multiple channels, parallel analysis · CPC title

• H01J49/0031 Primary

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title

• H01J49/0081

  Tandem in time, i.e. using a single spectrometer · CPC title

• H01J49/40

  Time-of-flight spectrometers (H01J49/36 takes precedence) · CPC title