ENVIRONMENTAL FATE OF CHIRAL POLLUTANTS - THE NECESSITY OF CONSIDERING STEREOCHEMISTRY

Many organic compounds regulated by environmental laws are chiral and are released into the environment as racemates. 3-Phenylbutanoic acid and mecoprop, two chiral pollutants, were enantioselectively degraded by pure cultures of microorganisms. This indicates the importance of a ssessing the environmental impact of stereoisomers separately, because selective enrichment of one of the enantiomers may occur in the envir onment. Field studies on the fate of highly polar, chiral compounds, l ike sulfophenylcarboxylates, are hampered by the lack of appropriate a nalytical methods for the separation of the enantiomers. Therefore, a method based on capillary electrophoresis with alpha-cyclodextrin as c hiral selector was developed to separate the enantiomers of such compo unds. In a field study at a Swiss waste disposal site, the fate of the chiral herbicide mecoprop was investigated. The enantiomeric ratio of (R)-mecoprop to (S)-mecoprop altered during groundwater passage of la ndfill leachate. This is a strong indication for in situ biodegradatio n. Our data imply that not only the enantiomers of a chiral drug or pe sticide may exert different effects on the biological targets, but als o their biodegradation and environmental fate may differ.