Patent ID: 7138624

Claim:
A method for accurate mass determination with ion trap/time-of-flight mass spectrometer provided with an ion source to ionize a sample, an ion trap to trap a plurality of ions differing in masses, and a time-of-flight mass spectrometer, the method for accurate mass determination with ion trap/time-of-flight mass spectrometer comprising steps of: generating ions of an analyte sample and a standard material by the ion source; introducing the ions of the analyte sample and the standard material together into the ion trap to trap them; selecting a precursor ion from among the ions of the analyte sample to leave the precursor ion and a standard material ion in the ion trap and eliminate other ions; exciting and dissociating the precursor ion to generate product ions; ejecting the precursor ion, the product ions, and the standard material ion trapped in the ion trap to introduce these ions from the ion trap into the time-of-flight mass spectrometer; and measuring a mass spectrum in the time-of-flight mass spectrometer, wherein correction for accurate masses of the product ions is carried out based on the standard material ion measured.