Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Anal Chem. 2011 Feb 1;83(3):1084-92. doi: 10.1021/ac1029117. Epub 2010 Dec 21.
Detection of explosives is important for public safety. A recently developed low-temperature plasma (LTP) probe for desorption and ionization of samples in the ambient environment ( Anal. Chem. 2008 , 80 , 9097 ) is applied in a comprehensive evaluation of analytical performance for rapid detection of 13 explosives and explosives-related compounds. The selected chemicals [pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), cyclo-1,3,5-trimethylenetrinitramine (RDX), tetryl, cyclo-1,3,5,7-tetramethylenetetranitrate (HMX), hexamethylene triperoxide diamine (HMTD), 2,4-dinitrotoluene, 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,6-dinitrotoluene, and 4-nitrotoluene) were tested at levels in the range 1 pg-10 ng. Most showed remarkable sensitivity in the negative-ion mode, yielding limits of detection in the low picogram range, particularly when analyzed from a glass substrate heated to 120 °C. Ions typically formed from these molecules (M) by LTP include M + NO(2), M, and M - NO(2). The LTP-mass spectrometry methodology displayed a linear signal response over three orders of magnitude of analyte amount for the studied explosives. In addition, the effects of synthetic matrices and different types of surfaces were evaluated. The data obtained demonstrate that LTP-MS allows detection of ultratrace amounts of explosives and confirmation of their identity. Tandem mass spectrometry (MS/MS) was used to confirm the presence of selected explosives at low levels; for example, TNT was confirmed at absolute levels as low as 0.6 pg. Linearity and intra- and interday precision were also evaluated, yielding results that demonstrate the potential usefulness and ruggedness of LTP-MS for the detection of explosives of different classes. The use of ion/molecule reactions to form adducts with particular explosives such as RDX and HMX was shown to enhance the selectivity and specificity. This was accomplished by merging the discharge gas with an appropriate reagent headspace vapor (e.g., from a 0.2% trifluoracetic acid solution).
爆炸物检测对于公共安全至关重要。最近开发的一种低温等离子体（LTP）探针可用于在环境中对样品进行解吸和离子化（Anal. Chem. 2008, 80, 9097），现已应用于对 13 种爆炸物和爆炸物相关化合物的快速检测的综合分析性能评估中。选择的化学物质[季戊四醇四硝酸酯（PETN）、三硝基甲苯（TNT）、环-1,3,5-三甲基-1,3,5-三硝基胍（RDX）、特屈儿、环-1,3,5,7-四甲基四硝胺（HMX）、六亚甲基三过氧二胺（HMTD）、2,4-二硝基甲苯、1,3-二硝基苯、1,3,5-三硝基苯、2-氨基-4,6-二硝基甲苯、4-氨基-2,6-二硝基甲苯、2,6-二硝基甲苯和 4-硝基甲苯]的检测水平在 1 pg-10 ng 范围内。大多数物质在负离子模式下表现出显著的灵敏度，在低皮克范围内检测到，尤其是在加热至 120°C 的玻璃基质上进行分析时。这些分子（M）通过 LTP 通常形成的离子包括M + NO(2)、M和M - NO(2)。LTP-质谱法对研究中的爆炸物在分析物数量的三个数量级范围内表现出线性信号响应。此外，还评估了合成基质和不同类型表面的影响。获得的数据表明，LTP-MS 允许检测痕量爆炸物并确认其身份。串联质谱（MS/MS）用于确认所选爆炸物在低水平下的存在；例如，TNT 被确认的绝对水平低至 0.6 pg。还评估了线性度以及日内和日间精密度，结果表明 LTP-MS 具有检测不同类别的爆炸物的潜在有用性和坚固性。通过将放电气体与适当的试剂顶空蒸汽（例如，来自 0.2%三氟乙酸溶液）合并，显示出离子/分子反应形成与特定爆炸物（如 RDX 和 HMX）的加合物可以提高选择性和特异性。
