Patent ID: 7928363

Claim:
A method of mass spectrometry comprising the steps of: (a) providing an ion source for generating parent or precursor ions; (b) passing said parent or precursor ions to a collision, fragmentation or reaction device comprising an Electron Capture Dissociation fragmentation device downstream of said ion source; (c) operating said Electron Capture Dissociation fragmentation device in a first mode of operation wherein at least some of said parent or precursor ions are fragmented upon interacting with electrons to produce fragment or daughter ions; (d) recording a mass spectrum of said fragment or daughter ions as a first mass spectrum; (e) switching, altering or varying said Electron Capture Dissociation fragmentation device to operate in a second mode wherein substantially fewer parent or precursor ions are fragmented; (f) recording a mass spectrum of ions emerging from or which have been transmitted through said Electron Capture Dissociation fragmentation device operating in said second mode as a second mass spectrum; and (g) repeating steps (c)-(f) a plurality of times.