Patent ID: 8269166

Claim:
An MS/MS mass spectrometer including a first mass separator for selecting, as a precursor ion, an ion having a specific mass-to-charge ratio from various kinds of ions, a collision cell for dissociating the precursor ion by making the precursor ion collide with a collision-induced dissociation gas, and a second mass separator for selecting an ion having a specific mass-to-charge ratio from various kinds of product ions created by dissociation of the precursor ion, and the MS/MS mass spectrometer further includes: a) a calibrating analysis execution means for collecting mass analysis data by analyzing a sample having a known mass-to-charge ratio by performing a mass scan in the first mass separator under a condition that a collision-induced dissociation gas is introduced into the collision cell while no substantial mass separation is performed in the second mass separator; b) a calibration information memory means for creating mass calibration information for the first mass separator unit, based on the mass analysis data collected by the calibrating analysis execution means, the mass calibration information reflecting a time delay of an ion in the collision cell, and for memorizing the mass calibration information; and c) an actual analysis execution means for collecting mass analysis data for a target sample by controlling a mass-scan operation of the first mass separator by using the mass calibration information memorized in the calibration information memory means, at least when a neutral loss scan or a precursor ion scan is performed.