MS/MS analysis using ECD or ETD fragmentation

Patent metadata

Field	Value
Publication number	US-9129783-B2
Application number	US-201314390451-A
Country	US
Kind code	B2
Filing date	Apr 5, 2013
Priority date	Apr 5, 2012
Publication date	Sep 8, 2015
Grant date	Sep 8, 2015

Abstract

A method of mass spectrometry is disclosed comprising providing a mixture of different analyte ions and supplying electrons or reagent ions to said mixture so as to transfer charge to the analyte ions. The transfer of charge causes at least some of the analyte ions to dissociate and others of the analyte ions not to dissociate, but to form intermediate ions of altered charge state. These intermediate ions are then isolated from other ions and excited so as to dissociate into daughter ions. The intermediate ions and their daughter ions are analyzed and associated with each other so that the intermediate can be identified from their daughter ions. The analyte ions can then be identified from the intermediate ions, since they differ only in charge state. The disclosed method enables analyte ions to be associated with their fragment ions, and therefore identified, without having to isolate individual analyte ions prior to their interactions with the electrons or reagent ions.

First claim

The invention claimed is:

1. A method of mass spectrometry comprising:
(a) providing a mixture of different analyte molecules or analyte ions;
(b) supplying electrons or reagent ions to said mixture of different analyte molecules or analyte ions so as to transfer charge from said reagent ions or electrons to said analyte molecules or ions, said transfer of charge causing at least some of said analyte molecules or analyte ions to dissociate and others of said analyte molecules or analyte ions not to dissociate but to form intermediate ions of altered charge;
(c) isolating at least some of said intermediate ions from other ions;
(d) exciting at least some of the isolated intermediate ions so as to cause them to dissociate into daughter ions; and
(e) mass analysing at least some of said intermediate ions and/or or mass analysing at least some of said daughter ions.

2. The method of claim 1 , wherein the electrons or reagent ions are supplied to the analyte molecules or analyte ions in an atmospheric pressure ion source or in an ion source or reaction cell that is maintained at a pressure selected from the group of >0.1 mbar; >10 mbar; >100 mbar; or about 1 bar.

3. The method of claim 1 , wherein the electrons or reagent ions cause said analyte molecules or analyte ions to dissociate via electron capture dissociation (ECD) or via electron transfer dissociation (ETD).

4. The method of claim 1 , wherein the intermediate ions are precursor analyte ions that have been reduced in charge due to interactions with said reagent ions or electrons.

5. The method of claim 1 , wherein the electrons or reagent ions are supplied to the analyte molecules or analyte ions in an ion source or reaction cell and wherein the intermediate ions are selectively transmitted downstream of the ion source or reaction cell and subsequently excited and dissociated into said daughter ions.

6. The method of claim 1 , comprising:
providing said analyte ions;
analysing said analyte ions without first exposing them to said electrons or reagent ions so as to generate a first signal;
exposing said analyte ions to said electrons or reagent ions so that some of said analyte ions form said intermediate ions, and mass analysing the resulting ions so as to generate a second signal;
comparing the first and second signals so as to determine a difference between the signals, the difference having been caused by the generation of said intermediate ions and serving to identify a characteristic of the ions which are the intermediate ions; and
performing said step of isolating at least some of said intermediate ions based on said characteristic determined by comparing said signals.

7. The method of claim 6 , wherein the first and second signals are generated by mass analysing the ions and the mass or mass to charge ratio of the intermediate ions is the characteristic determined by comparing said signals.

8. The method of claim 6 , comprising mass analysing the analyte ions to generate the first signal and mass analysing said resulting ions to generate the second signal; comparing the first and second signals so as to determine if one or more ion peaks present in both signals has shifted in mass to charge ratio between the signals; and determining that the ions which give rise to the one or more shifted peaks are intermediate ions.

9. The method of claim 1 , wherein the intermediate ions are isolated from the other ions using a mass filter to mass selectively transmit said intermediate ions.

10. The method of claim 9 , wherein the intermediate ions are isolated by setting an RF rod set so as to transmit said intermediate ions and filter other ions.

11. The method of claim 6 , wherein the first and second signals are generated using an ion mobility separator and the ion mobility of the intermediate ions is determined by comparing said signals and preferably used to isolate the intermediate ions.

12. The method of claim 1 , wherein both the intermediate ions and their daughter ions are analysed in a manner so as to associate the intermediate ions with their daughter ions.

13. The method of claim 12 , wherein at least some of the intermediate ions that have been dissociated to form daughter ions are identified from their daughter ions.

14. The method of claim 13 , wherein the identified intermediate ions are used to identify the analyte molecules or analyte ions from which these intermediate ions derived.

15. The method of claim 1 , wherein the intermediate ions are excited so as to dissociate by one or more of the following techniques: collision induced dissociation (CID); excitation by electromagnetic waves; excitation by X-rays; excitation by Infra Red or Ultra Violet waves; surface induced dissociation (SID); electron transfer dissociation; and electron capture dissociation.

16. The method of claim 1 , wherein the analyte ions or analyte molecules are from biomolecules.

17. The method of claim 16 , wherein the analyte ions or analyte molecules contain disulphide linked biomolecules.

18. The method of claim 1 , wherein said electrons are generated by using any one of: photo-ionisation; high voltage corona or glow discharges; or plasmas.

19. A method of mass spectrometry comprising:
providing a mixture of different analyte molecules or analyte ions;
supplying electrons or reagent ions to said mixture of different analyte molecules or analyte ions so as to transfer charge from said reagent ions or electrons to said analyte molecules or ions, said transfer of charge causing at least some of said analyte molecules or analyte ions to dissociate and others of said analyte molecules or analyte ions not to dissociate but to form intermediate ions of altered charge;
isolating at least some of said intermediate ions from other ions;
exciting at least some of the isolated intermediate ions so as to cause them to dissociate into daughter ions;
analysing at least some of the intermediate ions and at least some of their daughter ions so as to associate at least some of the intermediate ions with their daughter ions; and
identifying intermediate ions from their daughter ions.

20. The method of claim 19 , further comprising using the identified intermediate ions to identify the analyte molecules or analyte ions from which these intermediate ions derived.

21. A mass spectrometer comprising:
an ion source or reaction cell for receiving a mixture of different analyte molecules or analyte ions;
means for supplying electrons or reagent ions to said mixture of different analyte molecules or analyte ions in said ion source or reaction cell so as to transfer charge from said reagent ions or electrons to said analyte molecules or ions, said transfer of charge for causing at least some of said analyte molecules or analyte ions to dissociate and others of said analyte molecules or analyte ions not to dissociate but to form intermediate ions of altered charge;
means for isolating at least some of said intermediate ions from other ions;
means for exciting at least some of the isolated intermediate ions so as to cause them to dissociate into daughter ions; and
means for mass analysing at least some of said intermediate ions and/or or mass analysing at least some of said daughter ions.

22. A mass spectrometer comprising:
an ion source or reaction cell for receiving a mixture of different analyte molecules or analyte ions;
means for supplying electrons or reagent ions to said mixture of different analyte molecules or analyte ions in said ion

Assignees

• Micromass Ltd
• Univ British Columbia

Inventors

• Brown Jeffery Mark
• Robb Damon

Classifications

• H01J49/0031 Primary

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

• H01J49/0072

  by ion/ion reaction, e.g. electron transfer dissociation, proton transfer dissociation · CPC title

• H01J49/0054 Primary

  by an electron beam, e.g. electron impact dissociation, electron capture dissociation · CPC title

• H01J49/0045

  characterised by the fragmentation or other specific reaction · CPC title