Quadrupole mass analyzer

Abstract

As a control parameter given to a direct-current (DC) voltage generator (53) which generates a DC voltage for ion selection, a "mass-related offset" for allowing an adjustment of the offset for each mass-to-charge ratio is provided in addition to the "gain" and "common offset" which respectively determine the gradient and position of a scan line drawn on a stability diagram during a mass-scan operation. In an automatic adjustment operation using a standard sample, under the control of an automatic regulator (61), the "gain" and "common offset" are initially set, after which the "mass-related offset" for each mass-resolving power is determined so that the mass-resolving power will be substantially uniform, and these data are stored in a control data memory (52). In an analysis of a sample of interest, a quadrupole voltage controller (51) controls the DC voltage generator (53) and a radio-frequency (RF) voltage generator (54) according to the control parameters read from the memory (52). Even when the RF voltage V is non-linear due to the non-linearity of a wave-detector (56), the mass-resolving power can be made to be substantially uniform by varying the DC voltage U in the form of a polygonal line that resembles that non-linearity.

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 originating 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 op...

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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