四极杆离子光学和串联振荡电子学系统

Quadrupole Ion Optics and Series Oscillating Electronics System

  • 摘要: 四极杆和飞行时间质谱是液相色谱-质谱(LC/MS)、三重四极杆质谱(QQQ)和四极杆-飞行时间质谱(Q TOF)等质谱仪器中必备的核心部件,也是我国亟待研发的国产化仪器。目前,国内对质谱仪器的研制热情日益高涨,得到了国家相关部门的高度认可和广大研发人员的积极响应。本综述基于作者课题组多年的研制经验,从质谱仪器研发的角度介绍实现离子光学系统和电子学系统的技术原理。首先回顾四极杆的基本原理;然后着重讨论加工和装配精度对提高四极杆分辨率的重要性,以及四极杆尺寸选择对射频电压控制的影响;最后重点介绍四极杆串联振荡电子学系统以及在系统中起关键作用的阻抗匹配,希望能为质谱仪器研制提供参考。

     

    Abstract: Quadrupoles are essential components in mass spectrometry instruments, such as liquid chromatography mass spectrometry (LC/MS), triple quadrupole mass spectrometry (QQQ) and quadrupole time-of-flight mass spectrometry (Q TOF), and similar domestic instruments are severely lacked in China. At present, the domestic enthusiasm for the development of mass spectrometers is increasing, and the recommendations and slogans of “Making Chinese Mass Spectrometers” are put forward, which has been highly recognized and responded by the government and research personnel. This review focused on technical principles for quadrupole ion optics and electricity based on many years of author’s experience in the development of the core technology principles of mass spectrometry. Firstly, the theoretical basis of quadrupoles were introduced in brief. Next, the importance of mechanical accuracy in quadrupole processing and assembly were introduced in order to improve quadrupole resolution, including the effect of rod size selection on quadrupole radio frequency (RF) voltage control. Finally, we highlighted the quadrupole electronics with a serial oscillating model, and its impedance matching which played a key role in quadrupole performance. The core technical principle of the series RF oscillating circuit is that the two-stage series oscillation is applied. Two-stage voltage amplification can step up the voltage to the required amplitude in a relatively easy manner. Besides, the two-stage impedance matching can be realized between the low-resistance oscillation source and the high-resistance quadrupole load smoothly. The series oscillation uses a symmetrical RF oscillation source. The low internal resistance RF voltage source provides the primary RF voltage, which is boosted to the RF medium voltage through the first-stage series LC oscillation and obtains a higher load impedance. The RF medium voltage is coupled by a capacitance to the second stage series LC oscillation, boosted again to the required RF amplitude and matched to the impedance of quadrupole. RF radiation shielding is also an important part of the series oscillation process, which determines the quality of series oscillation. Series oscillations make it easier to obtain high RF voltages, and possible to analyze large mass molecules for quadrupoles.

     

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