用于低质荷比离子传输的射频四极杆导向装置的研制

Development of RF-only Quadrupole Ion Guide for Transmission of Low Mass-to-Charge Ratio Ions

  • 摘要: 离子传输系统是质谱仪的重要组成部分,主要作用是将离子高效率地传输到质量分析器。本工作研制了一种用于质子转移反应飞行时间质谱(PTR-TOF MS)系统的射频四极杆离子导向装置,四极杆长80 mm,杆半径2.6 mm,内切圆半径2.25 mm,该装置可针对性地实现低质荷比挥发性有机化合物(VOCs)离子的聚焦传输。利用SIMION 8.1离子光学模拟平台对装置的运行环境进行仿真,然后在自行搭建的测试平台上对装置的工作条件,如气压、频率和电压幅值进行测试。结果表明,仿真和测试结果具有较好的一致性,装置的工作气压范围较宽,在0.2~0.3 Pa时的传输效率最高;当频率为3~4 MHz,电压幅值(Vp-p)为500 V左右时,对丙酮、甲苯等低质荷比VOCs(<m/z 100)的传输效率接近76%,且离子束直径≤0.7 mm。该装置结构简单、成本低、传输效率高,具有潜在的实用价值,有望应用于PTR-TOF MS系统。

     

    Abstract: The ion guide system is an important part of the mass spectrometer, which main function is to efficiently transfer ions to the mass analyzer. In this work, a radio frequency quadrupole ion guide device for proton transfer reaction time-of-flight mass spectrometry (PTR-TOF MS) was developed and the quadrupole length was 80 mm, the rod radius was 2.6 mm, and the inscribed circle radius was 2.25 mm. This device realized focusing and transmission of volatile organic compounds (VOCs) with low mass-to-charge ratio. The movement of ions in the RF-only quadrupole device was simulated by SIMION 8.1 ion optical simulation software. The working conditions of the device, such as pressure, frequency and voltage amplitude, were tested on the home-built test platform. The results showed that the simulation and test had good consistency. The working pressure, frequency and amplitude of voltage were optimized to be 0.2-0.3 Pa, 3-4 MHz and about 500 V, respectively. The transmission efficiency of low mass-to-charge ratio VOCs (less than m/z 100) ions such as acetone and toluene was close to 76% with ion beam diameter no more than 0.7 mm. The device has the advantages of simple structure, low cost and high transmission efficiency, and which will be expected to be used in the PTR-TOF MS system.

     

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