Quadrupole-type mass spectrometer apparatus

Abstract

Provided is a quadrupole-type mass spectrometer apparatus, wherein "mass corresponding offsets" are provided, with which offsets can be adjusted for each of a plurality of mass-to-charge ratios, other than "gain" and "Common offset" for determining the inclination and position of a scanning straight line to be draw on a stable-state graph upon executing mass scanning, as control parameters to be given to a DC voltage generating unit (53) for generating DC voltage for selecting an ion. Upon executing automatic adjustment using a reference sample, the "gain" and the "Common offset" are determined first, and then, "mass corresponding offsets" are determined for each of the mass resolutions such that the mass resolutions will become roughly uniform, under the control of an automatic adjustment unit (61), and those control parameters are stored in a control data storage unit (52). Upon analyzing a target sample, a quadrupole voltage control unit (51) controls the DC voltage generating unit (53) and a high-frequency voltage generating unit (54) according to the control parameters read out from the storage unit (52). Even when a high-frequency voltage (V) becomes nonlinear due to nonlinearity of a demodulation unit (56), the DC voltage (U) can be changed into broken-line form that approximates that nonlinearity, making the mass resolution roughly uniform.

Description

technical field [0001] The present invention relates to a quadrupole mass spectrometer using a quadrupole mass filter as a mass analyzer for separating ions derived from a sample according to the mass-to-charge ratio (m / z). Background technique [0002] Generally, in a quadrupole mass spectrometer, various ions generated from a sample are introduced into a quadrupole mass filter to selectively pass only ions having a specific mass-to-charge ratio, and a detector detects the ions that pass through. Detection is performed to obtain an intensity signal corresponding to the amount of ions. [0003] As is well known, a general quadrupole mass filter is composed of four rod electrodes arranged around the ion optical axis and parallel to each other, and the sum of DC voltage and high-frequency voltage (AC voltage) is applied to the four rod electrodes respectively. get the voltage. The mass-to-charge ratio of ions that can pass through the space in the direction of the ion optica...

AI Technical Summary

Problems solved by technology

[0014] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a quadrupole mass spectrometer that can be used even when the linearity of the high-frequency voltage applied to the quadrupole mass filter with respect to the mass-to-charge ratio is poor. The uniformity of mass resolution can also be improved over the entire range of mass-to-charge ratios

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