MS/MS Analysis Using ECD or ETD Fragmentation

Patent metadata

Field	Value
Publication number	US-2016254130-A1
Application number	US-201415028202-A
Country	US
Kind code	A1
Filing date	Oct 9, 2014
Priority date	Oct 9, 2013
Publication date	Sep 1, 2016
Grant date	—

Abstract

A method of mass spectrometry is disclosed comprising: providing supercharged analyte ions; and supplying electrons or reagent ions to said analyte ions so as to transfer charge from said reagent ions or electrons to said analyte ions, said transfer of charge causing at least some of said analyte ions to dissociate. The charge transfer step is performed at a relatively high pressure and preferably substantially at atmospheric pressure.

First claim

1 . A method of mass spectrometry comprising:
(a) providing supercharged analyte ions; and (b) supplying electrons or reagent ions to said analyte ions so as to transfer charge from said reagent ions or electrons to said analyte ions, said transfer of charge causing at least some of said analyte ions to dissociate; wherein step (b) is performed at a pressure selected from the group of >0.1 mbar; >1 mbar; >5 mbar; >10 mbar; >100 mbar; about 1 bar; or substantially at atmospheric pressure.

2 . The method of claim 1 , wherein said step of providing supercharged analyte ions comprises adding a reagent to analyte and then ionising the analyte so as to produce
said analyte ions with a higher charge state than they would have been produced without having added the reagent to the analyte prior to ionisation.

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

4 . The method of claim 1 , said transfer of charge causing at least some of said analyte ions to dissociate and others of said analyte ions not to dissociate but to form intermediate ions of altered charge; the method further comprising:
(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 mass analysing at least some of said daughter ions.

5 . The method of claim 4 , wherein step (b) of claim 1 comprises supplying said reagent ions to a mixture of different analyte ions so as to cause the analyte ions to dissociate and/or to form the intermediate ions.

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

7 . The method of claim 4 , wherein the electrons or reagent ions are supplied to the 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.

8 . 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.

9 . The method of claim 8 , 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.

10 . The method of claim 8 , 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.

11 . The method of claim 4 , wherein the intermediate ions are isolated from the other ions using a mass filter to mass selectively transmit said intermediate ions.

12 . The method of claim 11 , wherein the intermediate ions are isolated by setting an RF rod set so as to transmit said intermediate ions and filter other ions.

13 . The method of claim 8 , 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.

14 . The method of claim 4 , 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.

15 . The method of claim 14 , wherein at least some of the intermediate ions that have been dissociated to form daughter ions are identified from their daughter ions.

16 . The method of claim 15 , wherein the identified intermediate ions are used to identify the analyte molecules or analyte ions from which these intermediate ions derived.

17 . The method of claim 4 , 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.

18 . The method of claim 1 , wherein the analyte ions are from biomolecules.

19 . The method of claim 18 , wherein the analyte ions contain disulphide linked biomolecules.

20 . 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.

21 . A method of mass spectrometry comprising:
providing a mixture of different supercharged analyte ions; supplying electrons or reagent ions to said mixture of different analyte ions in a region at a pressure selected from the group of >0.1 mbar; >1 mbar; >5 mbar; >10 mbar; >100 mbar; about 1 bar; or substantially at atmospheric pressure 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.

22 . The method of claim 21 , further comprising using the identified intermediate ions to identify the analyte molecules or analyte ions from which these intermediate ions derived.

23 . A method of mass spectrometry comprising:
(a) providing analyte molecules or analyte ions using a MALDI ion source; (b) supplying electrons or reagent ions to said 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 di

Assignees

• Micromass Ltd

Inventors

• Brown Jeffery Mark

Classifications

• H01J49/0031

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

• H01J49/164

  Laser desorption/ionisation, e.g. matrix-assisted laser desorption/ionisation [MALDI] (sample holders H01J49/0418) · CPC title

• H01J49/0054

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

• H01J49/0072 Primary

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

• H01J49/0045 Primary

  characterised by the fragmentation or other specific reaction · CPC title