A NEW TECHNIQUE FOR DECOMPOSITION OF SELECTED IONS IN MOLECULE ION REACTOR COUPLED WITH ORTHO-TIME-OF-FLIGHT MASS-SPECTROMETRY

A molecule ion reactor (MIR), i.e. a gas filled radio-frequency only q uadrupole with a longitudinal electrical field (RFQLEF), is used as an atmospheric pressure ionization interface for an orthogonal time-of-f light mass spectrometer (O-TOFMS), A new phenomenon of selective ion ' heating' in a MIR near Mathieu's instability threshold was found and c onfirmed by computer simulation, The 'heating' in collisions with buff er gas molecules leads to ion decomposition, In the case of multicharg ed ions, fragments with an m/z value higher than that of the parent io n have a stable motion and can be analysed by an O-TOFMS, Fragmentatio n of bradykinin and beta-endorphin molecular ions having a selected ch arge state is demonstrated, The spectra show clear 'ladder' structure, The phenomenon may be used as an alternative to tandem mass spectrome try (MS/MS) for molecule structure analysis. (C) 1997 by John Whey & S ons, Ltd.