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|1. (WO2017154062) GAS CHROMATOGRAPH MASS SPECTROMETER|
|Title:||GAS CHROMATOGRAPH MASS SPECTROMETER|
In the present invention, GC/MS measurement of a target sample is carried out under ionization using electron ionization (EI) (S1). Peaks are detected on a chromatogram based on the obtained data, and for each peak, a compound is identified through the comparison of the mass spectrum corresponding to the peak with a compound database (S2-S4). Compounds for which the similarity during identification was low are extracted as compounds to be measured, measurement windows are set so as to include the retention times of the peaks corresponding to the compounds, and a control program is created for carrying out chemical ionization (CI) only within the measurement windows (S5-S8). GC/MS measurement of the target sample is carried out while according to the control program, control is carried out so that within the measurement windows, a reagent gas is supplied to the inside of an ionization chamber and a filament for generating thermoelectrons is lit, and during time ranges outside of the measurement windows, the supply of the reagent gas is stopped and the filament is turned off (S9). Reagent gas ions are not generated during time ranges outside of the measurement windows, so adhesion of the ions to the inside of the ionization chamber, and the like, can be reduced, and stable measurement over a long period of time is possible.