Patent ID: 6512226
Filing Date: 2003-01-28
Classification: H01J

Abstract:
A method of analyzing a substance, the method comprising the step s of:(1) ionizing the substance to generate a stream of ions; (2) supplying the stream of ions to a quadrupole ion guide; (3) providing a buffer gas in the ion guide; (4) applying a radio frequency field by the quadrupole ion guide to maintain desired ions in a stable trajectory through the ion guide; (5) in addition to the radio frequency field applied in step (4), applying a periodic change to the ion guide to cause resonance excitation of ions having a selected m/z ratio whereby the selected ions acquire increased kinetic energies resulting in enhanced collision-induced dissociation with the buffer gas; (6) applying at least one additional excitation field in the quadrupole which additional excitation field is selected to cause resonance excitation of one of an addition ally selected parent ion and a fragment ion; and (7) analyzing the ion spectrum after fragmentation.