Mass spectrometer

A mass spectrometer, comprising:

• a sample introduction section for introducing a sample;
• an ion source for ionizing the sample introduced from the sample introduction section;
• an ion trap mass spectrometer for mass spectrometry of ions generated from the ion source;
• a data processing device having a data base for chemical substances and judging the presence or absence of an aimed chemical substance based on the mass spectral information obtained by the mass spectrometer;
• a device for applying a high frequency signal not containing resonance frequencies for a plurality of precursor ions which have different m/z values from different chemical substances but containing resonance frequencies of other ions, and having different amplitudes set on every frequency to an electrode constituting the mass spectrometer thereby controlling the selection of the plurality of precursor ions which have different m/z values from different chemical substances;
• and
• a device for applying a high frequency signal having amplitudes set individually on every resonance frequency of the plurality of precursor ions which have different m/z values from different chemical substances and superimposed with the resonance frequencies for the plurality of precursor ions which have different m/z values from different chemical substances to the electrode constituting the mass spectrometer thereby controlling the dissociation of the plural precursor ions which have different m/z values from different chemical substances,
• being adapted for selecting the plurality of precursor ions which have different m/z values from different chemical substances, obtaining mass spectra of a plurality of fragment ions obtained by dissociating the selected plurality of precursor ions which have different m/z values from different chemical substances and judging the presence or absence of the aimed chemical substance based on the mass spectra of the obtained plurality of fragment ions.