Patent ID: 7316931

Claim:
A method for discriminating between the mass of a labeled molecule or labeled molecule fragment and a mass of an unlabeled molecule or unlabeled molecule fragment in a sample, wherein the mass of the labeled molecule or labeled molecule fragment and the mass of the unlabeled molecule or unlabeled molecule fragment differ by less than one (1) amu, the method comprising the steps of: (a) accumulating a mass spectrum of said labeled molecule or labeled molecule fragment and said unlabeled molecule or unlabeled molecule fragment using a mass spectrometer, wherein the labeled molecule or labeled molecule fragment is labeled with a labeling moiety, said labeling moiety comprising at least one mass defect element having an atomic number from 17 to 77; and (b) discriminating between the mass of the labeled molecule or labeled molecule fragment and the mass of the unlabeled molecule or unlabeled molecule fragment in said mass spectrum based on the nuclear binding energy of the labeling moiety.