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首页> 外文期刊>Environmental Science & Technology >Development and Application of Pyrolysis Gas Chromatography/Mass Spectrometry for the Analysis of Bound Trinitrotoluene Residues in Soil
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Development and Application of Pyrolysis Gas Chromatography/Mass Spectrometry for the Analysis of Bound Trinitrotoluene Residues in Soil

机译：热解气相色谱/质谱法分析土壤中三硝基甲苯残留量的开发应用

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摘要

TNT (trinitrotoluene) is a contaminant of global environmental significance, yet determining its environmental fate has posed longstanding challenges. To date, only differential extraction-based approaches have been able to determine the presence of covalently bound, reduced forms of TNT in field soils. Here, we employed thermal elution, pyrolysis, and gas chromatography/mass spectrometry (GC/MS) to distinguish between covalently bound and noncovalently bound reduced forms of TNT in soil. Model soil organic matter-based matrixes were used to develop an assay in which noncovalently bound (monomeric) aminodinitrotoluene (ADNT) and diaminonitrotoluene (DANT) were desorbed from the matrix and analyzed at a lower temperature than covalently bound forms of these same compounds. A thermal desorption technique, evolved gas analysis, was initially employed to differentiate between covaiently bound and added 15{sup left}N-labeled monomeric compounds. A refined thermal elution procedure, termed "double-shot analysis" (DSA), allowed a sample to be sequentially analyzed in two phases. In phase 1, all of an added 15{sup left}N-labeled monomeric contaminant was eluted from the sample at relatively low temperature. In phase 2 during high-temperature pyrolysis, the remaining covalently bound contaminants were detected. DSA analysis of soil from the Louisiana Army Ammunition Plant (LAAP; ～5000 ppm TNT) revealed the presence of DANT, ADNT, and TNT. After scrutinizing the DSA data and comparing them to results from solvent-extracted and base/acid-hydrolyzed LAAP soil, we concluded that the TNT was a noncovalently bound "carryover" from phase 1. Thus, the pyrolysis-GC/MS technique successfully defined covalently bound pools of ADNT and DANT in the field soil sample.
机译：TNT（三硝基甲苯）是具有全球环境重要性的污染物，但确定其环境命运却带来了长期挑战。迄今为止，只有基于差异提取的方法才能确定田间土壤中是否存在共价结合的还原形式的TNT。在这里，我们采用热洗脱，热解和气相色谱/质谱（GC / MS）来区分土壤中TNT的共价结合和非共价结合还原形式。使用基于模型土壤有机物的基质开发了一种测定法，其中将非共价结合的（单体）氨基二硝基甲苯（ADNT）和二氨基硝基甲苯（DANT）从基质中解吸出来，并在比这些化合物的共价结合形式更低的温度下进行分析。最初采用热脱附技术，即析出的气体分析法，以区别于结合的固相和添加的15 N标记的单体化合物。改进的热洗脱程序称为“两次分析”（DSA），可以按两个阶段顺序分析样品。在阶段1中，所有添加的15 {N}标记的单体污染物均在相对较低的温度下从样品中洗脱出来。在高温热解的第二阶段中，检测到残留的共价键结合的污染物。来自路易斯安那州陆军弹药厂（LAAP；〜5000 ppm TNT）的土壤的DSA分析表明存在DANT，ADNT和TNT。在仔细研究了DSA数据并将其与溶剂萃取和碱/酸水解的LAAP土壤的结果进行比较之后，我们得出结论，TNT是第1阶段的非共价结合“残留”。因此，热解-GC / MS技术已成功定义田间土壤样品中ADNT和DANT的共价结合库。

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