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USE OF CAPILLARY ELECTROPHORESIS TO MEASURE THE ENANTIOSELECTIVE TRANSFORMATIONS OF CHIRAL ENVIRONMENTAL POLLUTANTS
Citation:
Garrison, A W., W J. Jones, AND J Avants. USE OF CAPILLARY ELECTROPHORESIS TO MEASURE THE ENANTIOSELECTIVE TRANSFORMATIONS OF CHIRAL ENVIRONMENTAL POLLUTANTS. Presented at EnviroAnalysis 2002, Toronto, Canada, May 27-31, 2002.
Impact/Purpose:
Extend existing model technologies to accommodate the full range of transport, fate and food chain contamination pathways, and their biogeographical variants, present in agricultural landscapes and watersheds. Assemble the range of datasets needed to execute risk assessments with appropriate geographic specificity in support of pesticide safety evaluations. Develop software integration technologies, user interfaces, and reporting capabilities for direct application to the EPA risk assessment paradigm in a statistical and probabilistic decision framework.
Description:
The enantiomers of chiral pollutants have identical physical and chemical properties but usually react selectively with enzymes or other chiral molecules. This enantioselectivity results in different rates of microbial transformation and differences in toxicity of the 2 (or more) enantiomers. To make more accurate risk assessments, it is necessary to understand the relative persistence and effects of the enantiomers; it follows that this understanding depends upon the ability to separate them. Enantiomeric separation can be accomplished by the use of chiral columns in GC and HPLC, and by chiral selectors in capillary electrophoresis (CE). This presentation will describe techniques for enantiomer separation by CE, and show applications to environmental problems. For example, we have applied CE with cyclodextrin selectors to the analysis of a variety of soil samples spiked with an organophosphorus pesticide (crufomate) and a phenoxyacid herbicide (dichlorprop) to follow their enantioselective microbial transformation kinetics. We have also used CE to follow the enantioselective loss of bromochloroacetic acid spiked into several surface water samples, which showed that in most cases the same enantiomer degraded fastest. Current studies involve CE to follow the loss of the enantiomers of dyfonate (an OP pesticide), imazaquin (an imidazolinone herbicide), and metalaxyl (an acylanilide fungicide) in soil slurries. CE, although less sensitive than GC or HPLC, has particular advantages that make it viable for following the transformation of chiral pollutants in benchtop experiments where the analyte can be dosed at a reasonably high concentration.