Unimolecular and collision-induced reactions of doubly charged porphyrins

Results from a tandem mass spectrometry (MS/MS) study, obtained with a reverse-geometry mass spectrometer, of the unimolecular and collision-induced reactions of doubly charged free-base and metal containing alkyl-substituted porphyrins formed by electron ionization are reported. These doubly charged porphyrin ions dissociate to yield both singly and doubly charged product ions via a number of reactions. This article classifies the major reactions observed, illustrating each with the appropriate spectra. Supplementary data from the same porphyrins, acquired with a tandem quadrupole MS/MS instrument, are also presented. The potential utility of some of these reactions as new methods for porphyrin analysis is discussed.