Massenspektrometer und massenspektrometrisches Verfahren

摘要

An improved method of parent ion scanning is disclosed. In one embodiment a quadrupole mass filter 3 upstream of a collision cell 4 is arranged to operate in a highpass mode. Parent ions transmitted by the mass filter 3 are fragmented in the collision cell 4 and detected by an orthogonal time of flight analyser 5 which obtains a daughter ion mass spectrum. Ions having a mass to charge ratio below the cutoff of the mass filter 3 are identified as daughter ions, and candidate parent ions may then be discovered and their identity confirmed by obtaining corresponding daughter ion spectra. In a second embodiment, the collision cell 4 alternates between high and low fragmentation and candidate parent ions can additionally be identified on the basis of the loss of a predetermined ion or neutral particle.