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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Production of toxaphene enantiomers by enantioselective HPLC after isolation of the compounds from an anaerobically degraded technical mixture.

Enantiomers of 12 chlorobornanes were separated on a chiral stationary HPLC phase. The investigated compounds included relevant chlorobornanes in technical toxaphene (Toxicant A and an unknown hepatachlorobornane), anaerobically mediated media such as sediment, soil, and sewage sludge (B6-923, B7-1001), as well as eight persistent compounds of technical toxaphene (CTTs) frequently detected in biological samples (B7-1000, B7-1453, B8-1412, B8-1413 or P-26, B8-1414 or P-40, B8-1945 or P-41, B8-2229 or P-44, and B9-1679 or P-50). Sufficient amounts of these 12 CTTs were not commercially available and had to be produced in our lab. Eight CTTs were obtained from sewage sludge that was spiked with technical toxaphene and kept under anaerobic conditions for four weeks. The samples were extracted with hexane followed by RP-HPLC fractionation. The resulting toxaphene pattern was significantly simpler than that of the technical mixture. CTTs that showed intense fragmentation in GC/ECNI-MS were preferably metabolized. Moreover, only one of the diastereomers that make Toxicant A (B8-806/B8-809 or P-42a/b) resisted degradation in sewage sludge. We found that the persistent component of Toxicant A is 2,2,5-endo,6-exo,8,9,9,10-octachlorobornane (B8-809 or P-42b). B9-1679 (P-50), B7-1453, and B8-1412 were earlier isolated from biological samples, and B7-1000 was isolated from naturally contaminated sediments. The fractions obtained after these procedures were suitable for enantioselective HPLC separations. The first eluting enantiomer was usually obtained as an enantiopure standard whereas the second eluting enantiomer also contained the other enantiomer. Attempts to determine the optical rotation with the help of a chiral HPLC detector failed. Elution orders of the enantiomers were established on three GC chiral stationary phases. Only the enantiomers of B7-1453 and B8-1945 (P-41) eluted in the same order from all CSPs while the others showed different enantiomer elution orders or were not resolved on one of the chiral GC stationary phases. The knowledge and consideration of these results is important for the interpretation of enantiomer ratios found in biological samples and comparison of literature data.[1]


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