Patent ID: 7595484

Claim:
A mass spectrometric method for use with a tandem mass spectrometer, the method comprising the steps of: ionizing a particular substance obtained by separating a sample; performing mass analysis of the ionized substance to obtain a spectrum; comparing said spectrum with a particular spectrum stored in advance and determining whether both the spectra match with each other or not by using a spectrum pattern matching judgment; and when a match is determined, further ionizing a particular ion within a particular time for detailed analysis, parent ions for MS n being selected based on a spectrum of MS n−1 (n≧2) and being subjected to a series of MS n , an intensity of each parent ion having the same mass-charge ratio m/z being integrated during the series of MS n within a time designated in advance by the operator, and when the integrated value exceeds a particular value, the ion having the relevant mass-charge ratio m/z being excluded from the parent ions for a subsequent one or more MS n .