不同膜材料在离子迁移谱用于爆炸物检测中的对比研究

Comparative study on the impact of different membrane materials on detection of explosives by ion mobility spectrometry.

膜材料对膜进样离子迁移谱(MI-IMS)的检测性能有较大影响。本研究基于自制的MI-IMS,通过研究目标物在膜内的渗透过程、考察目标物在膜内的传输模型,对比了聚二甲基硅氧烷(PDMS)膜和聚四氟乙烯(PTFE)膜在不同条件下对MI-IMS检测性能的影响,研究了这两种膜材料在不同厚度下对于2,4,6-三硝基甲苯(TNT)的透过效率以及对水蒸气的阻隔效果。研究表明,不同类型的膜材料在物质渗透过程中受检测条件影响的差异较大,相同条件下TNT在PDMS膜中的透过效率远高于PTFE膜,而PTFE膜对水蒸气表现出更好的阻隔效果。考虑仪器的灵敏度以及对水蒸气的阻隔效果,在膜温度为180℃,载气流速为200 mL/min的最优条件下,将厚度为100μm的PDMS膜应用于自制的膜进样离子迁移谱系统中对常见爆炸物进行检测,该仪器对TNT、硝化甘油(NG)、季戊四醇四硝酸酯(PETN)和环三亚甲基三硝胺(RDX)的检测限分别为109 pg、37 pg、172 pg和91 pg,实现了利用MI-IMS对爆炸物的稳定检测。

In this study,the effects of the carry gas flow rate and the membrane temperature on the permeation efficiency of the membranes with different thicknesses were investigated,the hydrophobic properties of Polydimethylsiloxane(PDMS)and polytetrafluoroethylene(PTFE)membranes with different thickness and the permeation efficiency of 2,4,6-Trinitrotoluene(TNT)in these membranes were studied by self-made MI-IMS.The results showed that the permeation efficiency of TNT in PDMS membrane was higher than in PTFE membrane at the same thickness,and PTFE membrane showed better hydrophobicity.The permeation efficiency of TNT was decreased and the hydrophobicity was improved with the membrane thickness increased.To achieve high sensitivity and stability of the instrument,the PDMS membrane was selected with thickness of 100μm and applied to the self-made MI-IMS to detect the common nitro-explosives.Under the optimal conditions(the membrane temperature was 180℃and the carry gas flow rate was 200 mL/min),the limits of detection(LOD)of TNT,Nitroglycerine(NG),Pentaerythritol Tetranitrate(PETN),and 1,3,5-Trinitrohexahydro-1,3,5-Triazine(RDX)were 109 pg,37 pg,172 pg,and 91 pg,respectively.The stable detection of trace explosives by MI-IMS was realized.