Patent ID: 8164053

Claim:
A mass analyzer, comprising; an ion trap for ejecting ions in a specific mass range; a collisional dissociation part for dissociating ions ejected from said ion trap; a mass analyzing part for performing a mass analysis of ions ejected from said collisional dissociation part; and a control part for controlling voltages applied to electrodes of said ion trap, said collisional dissociation part, and said mass analyzing part, wherein said control part changes the mass range of ions ejected from said ion trap by two or more scanning rates, as determined by a list, in each mass scanning time, and controls a set of voltages during a first period of a first scanning rate of said mass scanning time as ions are ejected, in which ions are introduced into the collisional dissociation part; and another set of voltages during a second period of a second scanning rate of said mass scanning time as ions are ejected, in which ions are not introduced into the collisional dissociation part.