Patent ID: 8704161

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) or multiple reaction monitoring (MRM) measurement configured to repeat a cycle of operation to sequentially change between a plurality of pre-set mass values for respective ions to by allowed to pass through the quadrupole mass filter, 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 combined voltage formed by adding a first DC voltage from the first DC voltage source and an AC voltage from the AC voltage source, to the quadrupole mass filter having four electrodes; a measurement sequence creation unit which rearranges a plurality of mass values designated for performing the SIM or MRM measurement, in a descending order of mass value, to create one cycle of an SIM or MRM measurement sequence, wherein the quadrupole driving unit is configured such that a voltage change response speed of the first DC voltage source is less than an amplitude change response speed of the AC voltage source; a pre-filter or an optical system disposed upstream of the quadrupole mass filter which introduces an ion into the quadrupole mass filter; and an input voltage control unit which applies a second DC voltage having a polarity opposite to that of a target ion, to the pre-filter or the ion optical system, in such a manner as to block the target ion from passing therethrough, during at least a part of a time-period between a completion of a first cycle of the SIM or MRM measurement and a start of a second cycle of the SIM or MRM measurement.