Analysis for volatile organic compounds by cryogenic oven trapping capillary gas chromatography

近年来，新型气相色谱（GC）仪器中出现了一种微机控制的将烤箱温度降至0℃以下的装置。该装置最初是为快速冷却烘箱而设计的，以减少分析时间。在我们的实验室中，我们使用它在低温烤箱温度下将挥发性有机化合物（VOCs）捕获在毛细管柱内；中孔径毛细管柱中最多可注入5ml顶空气相而无任何损失，灵敏度比传统顶空气相色谱法高10-100倍。除了上述高灵敏度之外，还可以实现更好的化合物分辨率（分离），这可能是因为VOCs在低温烤箱温度下被困在毛细管柱前部相当狭窄的区域中。该方法除具有上述高灵敏度、高分辨率外，操作简单，不需要特殊的气相色谱操作，可广泛应用于法医和环境毒理学。我们将该方法命名为毛细管气相色谱法（COT-GC）。对人体体液中氯仿、二氯甲烷、三氯乙烯、乙醚、溶剂稀释剂组分、二甲苯异构体、氰化物、乙醇、己烷、全麻等重要挥发性有机物的分析进行了研究，取得了较好的结果，并在多个国际毒理学期刊上发表了分析方法。本课题重点研究了利用COT-GC分析体液中烷基亚硝酸盐和苯丙胺衍生化分解产物苯乙烯及其相关化合物、烷基醇的新方法。我们已经在一些国际毒理学杂志上介绍了它们的敏感试验的详细程序。

Recently, a microcomputer-controlled device for lowering oven temperature below 0℃ has become available for new types of gas chromatography (GC) instruments. This device was originally designed for rapid cooling of an oven to reduce the time for analysis. In our laboratories, we are using it for trapping volatile organic compounds (VOCs) inside a capillary column at cryogenic oven temperatures ; as much as 5 mL of headspace vapor can be injected into a medium-bore capillary columun without any loss, giving sensitivity 10-100 times higher than that by the conventional headspace GC method. In addition to the above high sensitivity, much better resolution (separation) of compounds can be also achieved, probably because VOCs are trapped at a cryogenic oven temperature in a quite narrow zone of the front part of a capillary column.The method is recommendable for wide use in forensic and environmental toxicology, because it is simple and requires no special GC operations in addition to the above high sensitivity and high resolution. We named the method cryogenic oven trapping with capillary gas chromatography (COT-GC).We had studied analysis of some important volatile organic compounds (VOCs) such as chloroform, dichloromethane, trichloroethylene, diethyl ether, the components of solvent thinner, xylene isomers, cyanide, ethanol, hexane, general anesthetics in human body fluids, and we had got good results and had published analysis methods in many international journals of toxicology.In this research project, we especially studied new methods for analysis of styrene and related compounds, alkyl alcohol as decomposition products of alkyl nitrites and amphetamines with derivatization in human body fluids with COT-GC. We have presented each detailed procedure for their sensitive assays in some international journals of toxicology.