Use of mass spectral difference networks for determining charge state, adduction, neutral loss and polymerization

Abstract

A mass spectrometric analysis method comprises: (1) processing a mass spectrum to reduce the signals to monoisotopic values; (2) creating a list of differences between the monoisotopic values; (3) creating one or more lists of theoretical mass-to-charge differences among known adducts, charge states and polymerization states whose formation may be expected from various analyte molecules; (4) comparing the theoretical differences (line or edge in the network) to the list of differences from the mass spectrum and, where applicable, make and tabulate tentative species assignments; (5) assigning the mass spectral peaks to respective ion species in accordance with the redundancy of each assignment based on multiple independent calculated mass-to-charge differences pertaining to each peak; (6) choosing an ion species for further fragmentation or reaction in the mass spectrometer, based on the assigning; and (7) performing the fragmentation or reaction on the chosen ion species in the mass spectrometer.