|SOFT - TIAFT 1998||Scientific Session 8||Friday October 9, 1998|
|SENSITIVE DETERMINATIONS OF VOLATILE ORGANIC COMPOUNDS IN BODY FLUIDS BY CAPILLARY GAS CHROMATOGRAPHY WITH CRYOGENIC OVEN TRAPPING|
|Osamu Suzuki, Kanako Watanabe-Suzuki, Akira Ishii, Hiroshi Seno and Takeshi Kumazawa*|
Department of Legal Medicine, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu 431-3192, Japan
|The determination of volatile organic compounds (VOCs) in body fluids is frequently required in forensic science practice. VOCs are usually measured by gas chromatography (GC) with a headspace method. In most of the previous reports, conventional packed columns, which give relatively low sensitivity and poor separation, were used. With wide-bore capillary columns, only a 0.1-0.5 ml volume of headspace vapor can be injected; with medium-bore capillary columns, split injection giving 1-5% efficiency has to be used.
Recently, a microcomputer-controlled device for lowering oven temperature below 0oC has become available for new types of gas chromatographs. This device was originally designed for rapid cooling of an oven to reduce the time for analysis. In the present studies, we have used it for trapping VOCs inside a capillary column at cryogenic oven temperatures; as much as 5 ml of headspace vapor could be injected into a medium-bore capillary column without any loss, giving sensitivity 10-50 times higher compared with that by the previous headspace GC methods. In addition to the above high sensitivity, much better resolution (separation) of compounds could be also achieved, probably because VOCs were trapped, at a cryogenic oven temperature, in a quite narrow zone at the front end of a capillary column.
The method is appropriate for wide use in forensic and environmental toxicology applications requiring high sensitivity and high resolution, because it is simple and requires no special GC operations. Some successful data have obtained by the present capillary GC with cryogenic oven trapping for analyses of chloroform, solvent thinner compounds, hydrogen cyanide, ethanol and xylenes in human body fluids. A discussion of the method's utility and limitations will be presented.