Patent ID: 8957369
Filing Date: 2015-02-17
Classification: H01J

Abstract:
1. A method of tandem mass spectrometry, comprising the steps of: a) generating precursor ions in an ion source; b) guiding the precursor ions into an ion injector; c) ejecting the precursor ions from the ion injector towards an ion guide, via an ion gate, so that the precursor ions arrive at the said ion gate only once on their passage to the ion guide, the precursor ions arriving as a temporally separated plurality of ion packets each containing ions of a respective one of a plurality of different ion species; d) controlling the ion gate so as to sequentially select from the plurality of ion packets arriving at the ion gate, a subset of a plurality of ion packets deriving from a subset of precursor ion species of interest; e) mixing the selected subset of a plurality of ion packets in the ion guide; and f) analyzing the resulting ion population derived from the mixed selected subset of ion packets in a high resolution mass analyzer.