| 摘要 |
Ions originating from sample components are made to fly along a loop orbit (P) multiple times, and are deviated from the loop orbit (P) when a predetermined period of time has elapsed after the ejection of the ions. A time-of-flight spectrum recording unit (81) creates a time-of-flight spectrum based on the detected signal. If an overtaking of ions occurs on the loop orbit (P), the number of turns of peaks (ions) appearing on the spectrum cannot be determined. Given this factor, an isotopic peak detector (82) finds an isotopic peak group based on the time intervals and intensity ratio of a plurality of peaks appearing on the spectrum. A flight distance computation unit 83 uses the fact that the mass difference between adjacent peaks belonging to an isotopic peak group is 1 Da when ions are singly-charged, and computes the flight distance based on a predetermined formula. From the flight distance, a mass computation unit (84) computes the number of turns, and recomputes the flight distance which is structurally determined from this number of turns. Then, the mass computation unit (84) computes the mass of the target component. This enables an acquisition of the accurate mass free of the influence of an overtaking of ions and other factors.
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