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

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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.