Chromatograph mass spectrometer

A chromatograph mass spectrometer including a chromatograph for separating compounds in a sample and a mass analyzer for making an ion having a specific mass-to-charge ratio among ions originating from a compound in a sample separated by the chromatograph undergo a dissociation by a collision with collision gas within a collision cell and for detecting a product ion produced by the dissociation, the chromatograph mass spectrometer comprising:

• a) a gas supplier for supplying the collision gas to the collision cell;
• b) a preliminary measurement executer for changing a collision-gas pressure by the gas supplier in a continuous or stepwise manner, with a sample containing a same compound introduced in the mass analyzer, and for acquiring a signal strength of a product ion originating from the compound for every change in the collision-gas pressure;
• c) an optimum gas pressure extractor for determining the collision-gas pressure at which a peak value of the signal strength is maximized, based on a change in the signal strength corresponding to a change in the collision-gas pressure obtained by the preliminary measurement executer;
• and
• d) an analysis controller for controlling the gas supplier, using the optimum collision-gas pressure obtained by the optimum gas pressure extractor, so as to regulate the collision-gas pressure in a measurement in which a sample containing the compound is introduced into the chromatograph, at least when the compound is introduced from the chromatograph into the mass analyzer.