| 摘要 |
An analyzer previously inputs, from an input part (25), the mass of a fragment removed by the first cleaving, as a precursor ion selection standard in the second cleaving, together with other analysis conditions. Upon the start of an automatic analysis, a control unit (21) successively carries out an MS1 analysis, an MS2 analysis, and an MS3 analysis. During this process, a data processing part (23) determines the valence of each ion species corresponding to peaks in a mass spectrum obtained in the MS1 analysis. After the completion of the MS2 analysis, a search is made for an ion species satisfying the selection standard among the ion species corresponding to peaks in a mass spectrum obtained by the MS2 analysis by taking into consideration the above determined valence. The ion species is selected as a precursor ion in the second cleaving in the MS3 analysis. Thus, an improved analysis efficiency and the provision of highly accurate information about chemical structures can be realized by automatically selecting a precursor ion to be selected and cleaved in each stage of MSn analysis according to the mass of a fragment removed by the cleaving of the preceding stage, regardless of the valence of the object ion.
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