Mass analysis method and mass analysis system

Abstract

A measurement is performed in a no-passing mode, in which ions having different masses are prevented from making a complete turn through a loop orbit, to obtain a time-of-flight spectrum without the passing of ions having different masses (Sand S). From the time of flight and other information of the peaks appearing on the time-of-flight spectrum (S), the number of turns and the time of flight in the loop-turn mode are predicted. Based on this prediction, a set of segments are defined on a time-of-flight spectrum in the loop-turn mode. The time widths of those segments are determined taking into account the spreads of the time widths of the aforementioned peaks. Since the number of turns is unique within each segment, the numbers of turns and the masses of the peaks can be uniquely determined as long as none of the segments overlap each other. Accordingly, it is determined whether there is any overlapped portion in the segments defined on the time-of-flight spectrum in the loop-turn mode under provisionally predetermined conditions. When a condition under which no overlapping occurs has been found, the segment setting is fixed (S-S). As a result, the timing for switching an ejection switch, which is used for ejecting ions from the loop orbit, is also determined. Based on this timing, a measurement in the loop-turn mode is performed (S).