MS MS PARENT SCANS ON A QUADRUPOLE ION TRAP MASS-SPECTROMETER BY SIMULTANEOUS RESONANT EXCITATION OF MULTIPLE IONS

A parent ion scan has been developed for a quadrupole ion trap mass spectrometer (ITMS) which makes it possible to obtain a conventional parent ion spectrum following a single ionization event. Two resonant excitation waveforms were applied simultaneously across the end-cap electrodes of an ITMS. One of the resonant excitation waveforms is applied at a frequency and voltage chosen to cause rapid ejection of a selected daughter ion. The frequency of the second waveform is scanned to induce sequentially resonant excitation collision-induced dissociation (CID) of a series of parent ions. Those ions which undergo CID to produce the selected daughter ion will be detected as parent ions.