Quadrupole mass spectrometer

Abstract

A quadrupole mass spectrometer includes: an ion source for generating ions; a quadrupole mass filter for selectively passing object ions having a predetermined mass number among the ions from the ion source; an ion detector for detecting the object ions; an ion converging lens placed between the quadrupole mass filter and the ion detector; and a voltage source for applying an optimal voltage to the ion converging lens, wherein the voltage has a polarity opposite to that of the object ions and the absolute value of the voltage is larger than that of a voltage at which the converging efficiency of the object ions is the largest. With respect to the overall S/N ratio, the optimal state is achieved when the optimal converging voltage which is greater than the maximum converging voltage is applied to the ion converging lens.

Dependencies are inferred from the claim text.