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The pesticide toxaphene with a total worldwide production of 1.3 Mt is found in the aquatic environment with a widespread, global distribution. Its analysis is difficult due to its complex character. A technical toxaphene mixture and a number of biological samples were analyzed by multidimensional gas chromatography (MDGC). Four different column combinations were used: DB5/DX4, DB5/FFAP, Ultra 2/DX4, and Ultra 2/Rtx 2330. The technical mixture consists of at least 246 congeners, while only 107 peaks were found in a one-dimensional GC/ECD chromatogram. The major peaks present in the technical mixture and biological samples mostly consist of 2-10 toxaphene congeners. These results show that in most cases single-column chromatography is not suitable for a congener-specific determination of the toxaphene congeners. The Rtx 2330 column is recommended as the best choice as a second column in MDGC of toxaphene, particularly because of its stability at higher temperatures and because of a slightly better separation, although the differences in results obtained with the different column combinations were relatively small. The relatively high concentrations of toxaphene in European fish, which may even lead to exceeding the tolerance levels for human consumption, and in marine mammals demand a proper monitoring of total toxaphene and individual CHBs in relevant samples from European aquatic ecosystems.

The analysis of toxaphene, a highly complex mixture of chlorinated bornanes, bornenes and camphenes, is a challenging problem, especially as individual congeners are present at trace levels in biota and other relevant samples. The complicated nomenclature of the compounds of interest is briefly discussed. Gas chromatographic techniques are the most important tools in toxaphene analysis because of their high resolution. The main focus of attention is devoted to important steps in the GC-based analytical procedure, such as sample preparation and injection, separation by single-column and multidimensional GC, both heart-cut and comprehensive, and detection by electron capture and, increasingly, MS-based detection/identification. The gradual shift from total toxaphene to individual compound analysis is discussed, and the growing interest in enantiomer-selective separations is highlighted. The problems encountered when selecting appropriate indicator compounds for rapid toxaphene screening are also addressed.

SummaryComprehensive gas chromatography is an excellent technique for separating complex mixtures. If, however high-boiling compounds such as polychlorinated biphenyls have to be analysed, proper adjustiment of the temperature of the modulator turns out to be very important in maintaining the performance of the system. It is shown that miniaturisation of the column-to-modulator coupling, adequate selection of the modulating conditions and, for halogenated compound mixtures, the use of a micro electron-capture detector, can solve experimental problems previously encountered with high boilers.