Patent ID: 9373487
Filing Date: 2016-06-21
CPC Classification: H01J

Claim Text:
1. A mass spectrometer having one or more ion transport optical systems for transporting ions by an effect of an electric field between an ion source and an ion detector, the mass spectrometer being capable of performing an SIM or MRM measurement in which an operation of sequentially performing a mass spectrometry on each of a plurality of ions having previously specified mass-to-charge ratios is cyclically performed, and the mass spectrometer comprising: a) a voltage generator for applying a direct-current voltage corresponding to the mass-to-charge of an ion to be monitored, to at least one of the ion transport optical systems in the SIM or MRM measurement; and b) a controller for controlling the voltage generator so that, in a pause time during which collection of detection data by the ion detector is suspended in conjunction with a switching of the mass-to-charge ratio of the ion to be monitored, if a polarity of the ion to be monitored in an SIM or MRM measurement is unchanged before and after the switching of the mass-to-charge ratio, then the direct-current voltage applied to the at least one ion transport optical system, while being switched from one specific level to another specific level in the pause time, is temporarily changed to either a level at which the direct-current voltage has a polarity different from the polarity of the direct-current voltage at those specific levels, or a level at which the direct-current voltage has the same polarity as the direct-current voltage at those specific levels yet has a smaller absolute value than the direct-current voltage at any of those specific levels.