微波诱导等离子体离子迁移谱用于痕量爆炸物检测的研究

Microwave Induced Plasma Ionization Ion Mobility Spectrometry for Detection of Trace Explosives

基于微波诱导等离子体离子源,结合自制的离子迁移谱仪,探讨了负离子模式下反应离子的组分及形成机理,并首次将其应用于痕量爆炸物的快速检测。研究结果表明,等离子体维持气流速会影响反应离子的组分、强度及仪器的灵敏度;通过对比不同等离子体维持气流速下的空气背景迁移谱图、质谱图和季戊四醇四硝酸酯(PETN)的迁移谱图,优化了等离子体维持气流速(300 mL/min);此时反应离子峰的强度高达4 n A(脉冲宽度100μs),主要成分为NO_3^-。在优化条件下,系统考察了微波诱导等离子体离子迁移谱仪对爆炸物检测的响应线性范围及检出限。本方法对硝化甘油(NG)和PETN的线性范围分别为0.1~10.0 ng和0.1~5.0 ng,对NG、环三亚甲基三硝胺(RDX)、PETN、2,4,6-三硝基甲苯(TNT)、2,4-二硝基甲苯(2,4-DNT)的检出限(S/N=3)分别为8、14、12、14和13 pg,实现了痕量爆炸物的快速检测。

The development of safe and high-performance ionization source as an alternative is highly demanded. In this work,a negative ion mode of microwave induced plasma ionization ion mobility spectrometer（ MIPI-IMS） was developed. The components of reactant ions were investigated in negative ion mode.Experiments showed that the reactant ions and the sensitivity in detecting pentaerythritol tetranitrate（ PETN）were mainly influenced by the discharge gas flow rate. The comparison between the background of air and the mobility spectrum of PETN were displayed under different discharge gas flow rates. The optimized discharge gas flow rate was 300 mL/min. The reactant ion was mainly NO3^-,which was confirmed by mass spectrometry.The signal intensity was higher than 4 n A with gate pulse width of 100 μs under the optimized parameters.Finally,the MIPI-IMS was used in the detection of trace explosives such as nitroglycerine（ NG）,1,3,5-trinitrohexahydro-1,3,5-triazine（ RDX）,pentaerythritol tetranitrate（ PETN）,2,4,6-trinitrotoluene（ TNT）,and 2,4-dinitrotoluene（ 2,4-DNT）. The linear range for MIPI-IMS in detecting NG and PETN were 100 pg-10 ng and 100 pg-5 ng respectively. The limits of detection of NG,2,4-DNT,TNT,RDX and PETN were 8 pg,14 pg,12 pg,14 pg and 13 pg,respectively.