Patent ID: 8026476

Claim:
A mass analyzing method, using a mass spectrometer capable of an MS n analysis in which a precursor ion originating from a target substance is dissociated for n−1 stages (where n is an integer equal to or more than two) and a product ion generated by a dissociation is mass analyzed, for performing an analysis of a molecular structure and composition of the target substance based on data collected by the mass spectrometer, comprising: establishing preliminary information for a variety of ions generated in a dissociation process based on previously known information of the target substance, the preliminary information being a correspondence relationship between a specified mass and a composition formula derivable from the target substance; checking whether or not a mass of a product ion obtained by an MS m (where m is an integer satisfying 2≦m≦n) analysis corresponds to the specified mass given by the preliminary information; and in a case where a result of the checking is positive, determining a composition formula of the product ion by using the preliminary information and then deducing a composition of the target substance.