DETERMINATION OF DAUGHTER ION FORMULAS BY MULTIPLE STAGES OF MASS-SPECTROMETRY

The ability to obtain daughter ion formulas via comparison of MSn spectra of parent ions containing only 12C with those of parent ions with one 13C (from the natural 13C abundance) is shown for cases in which isobaric interferences with the 13C-containing ion preclude the use of the conventional tandem mass spectrometric approach. This method allows the presence of isobaric daughter ions to be ascertained, and unexpected, complex dissociation pathways to be identified. A three-dimensional quadrupole ion trap is used for these experiments. Its high tandem mass spectrometry efficiency makes possible this type of experiment. © 1990 American Society for Mass Spectrometry.