微波诱导等离子体离子迁移谱仪性能及影响因素的研究

离子迁移谱仪的性能受到多种因素的影响,如漂移管电场强度离子门脉冲宽度、离子源工作条件、漂移管尺寸、离子门加工工艺和屏蔽网透过率等。在实际应用中需要对漂移管电场强度和离子门脉冲宽度进行调整以平衡灵敏度和分辨率。本研究详细研究了漂移管电场强度和离子门脉冲宽度对微波诱导等离子体离子迁移谱( MIPI-IMS)分辨率和灵敏度的影响。实验结果表明,存在一个最佳电场强度值使得分辨率达到最大,而且不同离子门脉冲宽度对应的最佳电场强度值不同；增大电场强度和离子门脉冲宽度有利于灵敏度的提升。与其它离子流较弱的离子源相比,离子流较大的微波诱导等离子体离子源在实际应用中对离子门脉冲宽度和漂移管电场强度有更多的选择。此研究结果有助于MIPI-IMS仪器性能的提升。将异丙醇用于测试MIPI-IMS的性能,结果表明,MIPI-IMS在保持较低检出限(7.7×10-11, V/V)的同时,分辨率可以达到66。

Research of Influence Factors on Performance of Microwave Induced Plasma Ionization Ion Mobility Spectrometry

The performance of an ion mobility spectrometer ( IMS) was influenced by several factors such as drift field strength, gate pulse width, the operational parameters for ion source, dimensions of the drift tube, the machining quality of ion gate and the transmission of aperture grid. The gate pulse width and drift field strength needed to be tuned to balance the selectivity and sensitivity in real applications. This study investigated the influence of drift field strengths and the gate pulse widths on both selectivity and sensitivity of microwave induced plasma ionization ion mobility spectrometry ( MIPI-IMS ) made by our laboratory. Experimental results showed that there existed a drift field strength that made the resolving power reach the best. Moreover, the drift field strength for the best resolution was different from each other under different gate pulse widths. Increasing the drift field strength and gate pulse width was propitious to improve the sensitivity of MIPI-IMS. In comparison with other ion source with weak ion current, the MIPI source had strong ion current, which enabled the MIPI-IMS work in wider range in drift field strength and gate pulse width in practice. The results were helpful for the improvement of the performance of MIPI-IMS. Finally, 2-propanol was used to test the performance of the MIPI-IMS. The results showed that the limit of detection of MIPI-IMS could reach 7. 7 ×10-11(V/V) and the resolution was 66.