Quadrupole type mass spectrometer

Abstract

A quadrupole power source which applies a voltage to each electrode (2a-2d) of a quadrupole mass filter (2) receives inputs of an m / z-axis correction coefficient Mcomp1 and a V-voltage correction coefficient Vcomp1 in addition to a power supply controlling voltage Qcont according to the m / z of a target ion. Vcomp1 is a reciprocal of the ratio by which a frequency is changed, while Mcomp1 is the square of the ratio by which the frequency is changed. In a detection gain adjuster section (4C), a multiplier (421) multiplies an output Vdet' of a V-voltage adjusting amplifier (405) by Vcomp1, whereby the radio-frequency voltage produced by a radio-frequency power supply section (4A) is maintained at the same level even when the set frequency of a signal generator (411) is changed in order to tune an LC resonance circuit. Furthermore, in the radio-frequency power supply section, a multiplier (420) multiplies Qcont by Mcomp1, whereby an optimal voltage for mass selection is maintained even when the set frequency is changed. Thus, high mass-resolving power and high mass accuracy are automatically maintained even when the set frequency is adjusted for the purpose of tuning.

Description

technical field [0001] The present invention relates to a quadrupole mass spectrometer using a quadrupole mass filter as a mass separator for separating ions according to the mass-to-charge ratio m / z. Background technique [0002] The quadrupole mass spectrometer is a mass spectrometer using a quadrupole mass filter in order to separate ions based on the mass-to-charge ratio. exist Figure 6 A schematic structure of a quadrupole mass spectrometer is shown in . Various ions generated from a sample in an ion source 1 are introduced into a quadrupole mass filter 2 composed of four rod electrodes 2 a , 2 b , 2 c , and 2 d via a not-shown ion transport optical system. A voltage ±(U+V·cosωt) obtained by superimposing a high-frequency voltage ±V·cosωt and a DC voltage ±U is applied to the four rod electrodes 2a to 2d from the quadrupole power supply unit 4, and only Ions with a specific mass-to-charge ratio selectively pass through the quadrupole mass filter 2 . The detector 3 d...

AI Technical Summary

Problems solved by technology

In the method (1), there is a problem that in order to be able to change the inductance of the coils 10, 12 and the capacitance of the capacitors 11, 13 with high precision, it is necessary to use expensive components, and it is difficult to have stable performance due to variations in the characteristics of the components.

Figure 10 (a) is from Figure 9 The state of (b) is an actual measurement example when the V voltage is adjusted to return to its original state, but the m / z axis is shifted

[0020] Also, the m / z axis shifts even when the U voltage is changed so that U / V is fixed

Figure 10 (b) is from Figure 10 The state of (a) further adjusts the U voltage to the actual measurement example when U / V is fixed, but the m / z axis still shifts

Images