Patent ID: 8735806

Claim:
A mass-analyzing method using a mass spectrometer capable of an MS/MS analysis in which a precursor ion originating from a target substance is dissociated and product ions generated by the dissociation are mass analyzed, for analyzing a composition of the target substance based on data obtained by the mass spectrometer, comprising: a) setting an unknown substance, whose composition has been deduced by using a result of a mass analysis, to be a precursor ion, and performing an MS/MS analysis on the precursor ion; b) determining kinds of constituent elements and a number of atoms of each constituent element of the unknown substance based on the deduced composition of the unknown substance; c) computing a mass of each of possible fragment ions of the precursor ion based on the determined kinds of constituent elements and the number of atoms of each constituent element of the unknown substance by summing individually mass values of the determined kinds of constituent elements in various combinations permitted by the number of atoms of each constituent element, wherein the possible fragment ions are wholly made up of discrete units of the constituent elements; d) verifying whether a mass of one or more product ions appearing on a mass spectrum obtained by the MS/MS analysis exists in the computed mass of possible fragment ions; and e) determining a reliability of the composition deduced for the unknown substance based on the verification result.