Patent ID: 8716659

Claim:
A quadrupole mass spectrometer equipped with a quadrupole mass filter for allowing an ion having a specific mass to selectively pass therethrough and a detector for detecting the ion passing through the quadrupole mass filter, and designed to perform a selected ion monitoring (SIM)/scan alternate measurement which is configured to alternately perform an SIM measurement configured to sequentially change between a plurality of pre-set mass values for respective ions to be allowed to pass through the quadrupole mass filter, and a scan measurement configured to continuously change a mass value for an ion to be allowed to pass through the quadrupole mass filter, over a given mass range, the quadrupole mass spectrometer comprising: a quadrupole driving unit comprising: a first voltage-variable DC voltage source; and an amplitude-variable AC voltage source, wherein the quadrupole driving unit configured to apply a voltage formed by adding a first DC voltage from the first DC voltage source and an AC voltage from the AC voltage source, to four electrodes constituting the quadrupole mass filter, and wherein a voltage change response speed of the first DC voltage source is less than an amplitude change response speed of the AC voltage source; and a measurement sequence creation unit which, to create an SIM/scan alternate measurement sequence, i) rearranges a plurality of mass values designated for performing the SIM measurement, in a descending order of mass value; ii) with respect to each of the plurality of rearranged mass values, calculates a corresponding settling time-period based on a mass-value difference between each mass value and the other mass value which is used for a measurement to be performed just before a measurement for each mass value; iii) calculates a measurement time-period per mass value in the SIM measurement, based on an interval span assigned to the SIM measurement within a duration of one cycle of the SIM/scan alternate measurement, each of the settling time-periods calculated in ii), and a total number of the mass values to determine a control sequence in the interval span assigned to the SIM measurement; and iv) in the other interval span assigned to the scan measurement within the one cycle duration of the SIM/scan alternate measurement, sets a continuous change in mass value in an ascending direction over a mass range designated for performing the scan measurement.