Method of charge reduction of electron transfer dissociation product ions

Patent metadata

Field	Value
Publication number	US-9070539-B2
Application number	US-201314145621-A
Country	US
Kind code	B2
Filing date	Dec 31, 2013
Priority date	Jun 5, 2008
Publication date	Jun 30, 2015
Grant date	Jun 30, 2015

Abstract

A mass spectrometer is disclosed wherein highly charged fragment ions resulting from Electron Transfer Dissociation fragmentation of parent ions are reduced in charge state within a Proton Transfer Reaction cell by reacting the fragment ions with a neutral superbase reagent gas such as Octahydropyrimidolazepine.

First claim

The invention claimed is:

1. A mass spectrometer comprising:
a cell arranged and adapted to fragment ions by Electron Capture Dissociation and to generate first ions; and
a first device arranged and adapted to react said first ions with one or more neutral, non-ionic or uncharged superbase reagent gases or vapours in order to reduce a charge state of said first ions, wherein said first device comprises a first ion guide comprising a plurality of electrodes, and wherein a majority of said first ions comprise b-type product ions, b-type fragment ions, y-type product ions or y-type fragment ions resulting from the fragmentation of parent or analyte ions by Electron Capture Dissociation.

2. A mass spectrometer as claimed in claim 1 , wherein said first device comprises a Proton Transfer Reaction device.

3. A mass spectrometer as claimed in claim 1 , wherein, in use, either: (i) protons are transferred from at least some of said first ions to said one or more neutral, non-ionic or uncharged superbase reagent gases or vapours; or (ii) protons are transferred from at least some of said first ions which comprise one or more multiply charged analyte cations or positively charged ions to said one or more neutral, non-ionic or uncharged superbase reagent gases or vapours whereupon at least some of said multiply charged analyte cations or positively charged ions are reduced in charge state.

4. A mass spectrometer as claimed in claim 1 , wherein said one or more neutral, non-ionic or uncharged superbase reagent gases or vapours are selected from the group consisting of: (i) 1,1,3,3-Tetramethylguanidine (“TMG”); (ii) 2,3,4,6,7,8,9,10-Octahydropyrimidol[1,2-a]azepine {Synonym: 1,8-Diazabicyclo[5.4.0]undec-7-ene (“DBU”)} ;
and (iii) 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (“MTBD”){Synonym: 1,3,4,6,7,8-Hexahydro-1-methyl-2H-pyrimido[1,2-a]pyrimidine}.

5. A mass spectrometer as claimed in claim 1 , wherein said first ions comprise or predominantly comprise one or more of the following: (i) multiply charged ions; (ii) doubly charged ions; (iii) triply charged ions; (iv) quadruply charged ions; (v) ions having five charges;
(vi) ions having six charges; (vii) ions having seven charges; (viii) ions having eight charges; (ix) ions having nine charges; (x) ions having ten charges; or (xi) ions having more then ten charges.

6. A mass spectrometer as claimed in claim 1 , further comprising a DC voltage device which is arranged and adapted to apply one or more first transient DC voltages or potentials or one or more first transient DC voltage or potential waveforms to at least some of said plurality of electrodes comprising said first ion guide.

7. A mass spectrometer as claimed in claim 1 , further comprising a RF voltage device arranged and adapted to apply a first AC or RF voltage having a first frequency and a first amplitude to at least some of said plurality of electrodes of said first ion guide such that, in use, ions are confined radially within said first ion guide.

8. A method of mass spectrometry comprising:
fragmenting ions by Electron Capture Dissociation and generating first ions; and
reacting said first ions with one or more neutral, non-ionic or uncharged superbase reagent gases or vapours in order to reduce a charge state of said first ions, wherein a majority of said first ions comprise b-type product ions, b-type fragment ions, y-type product ions or y-type fragment ions resulting from the fragmentation of parent or analyte ions by Electron Capture Dissociation.

Assignees

• Micromass Ltd

Inventors

• Chen Weibin
• Chakraborty Asish B
• Gebler John Charles
• Brown Jeffery Mark

Classifications

• H01J49/165

  Electrospray ionisation · CPC title

• H01J49/062

  Ion guides (linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421) · CPC title

• H01J49/36

  Radio frequency spectrometers, e.g. Bennett-type spectrometers, Redhead-type spectrometers · CPC title

• H01J49/0095 Primary

  Particular arrangements for generating, introducing or analyzing both positive and negative analyte ions (ion/ion reactions H01J49/0072) · CPC title

• H01J49/0072 Primary

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