Patent ID: 7544931

Claim:
A mass-analyzing method for analyzing a molecular structure and/or composition of a sample, using a mass spectrometer capable of an MS n analysis in which a precursor ion originating from a sample to be analyzed is dissociated into fragment ions by (n−1) steps (where n≧3) and then the fragment ions are subjected to a mass-analyzing process, which is characterized in that it comprises: a) a candidate X deduction step for deducing candidates X of a component corresponding to the precursor ion obtained by an MS 1 analysis in which no dissociating operation is performed, on a basis of a mass of the precursor ion; b) a candidate Y deduction step for deducing candidates Y of a component corresponding to the fragment ion obtained by an MS m analysis (where 2≦m≦n), on a basis of a mass of that fragment ion; c) a candidate Z deduction step to be performed when a number of the candidates Y is equal to or smaller than a predetermined value, where the step includes sub-steps of calculating a difference between the mass of the fragment ion obtained by an MS p analysis (for p=2 to m) and the mass of a precursor or fragment ion obtained by an MS p-1 analysis and then deducing candidates Z of a component corresponding to the aforementioned difference in mass; and d) a narrowing step for narrowing down the candidates X by using at least the candidates Y and Z, and the number m is increased step by step from 2 up to n until the number of the candidates X becomes equal to one, or equal to or smaller than a predetermined value.