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APPLICATIONS OF CAPILLARY ELECTROPHORESIS TO THE STUDY OF CHIRAL ENVIRONMENTAL POLLUTANTS: ENANTIOMER SEPARATION AND MEASUREMENTS OF ENANTIOSELECTIVITY
Citation:
Garrison, A W. APPLICATIONS OF CAPILLARY ELECTROPHORESIS TO THE STUDY OF CHIRAL ENVIRONMENTAL POLLUTANTS: ENANTIOMER SEPARATION AND MEASUREMENTS OF ENANTIOSELECTIVITY. Presented at EnviroAnalysis 2000, Ottawa, Canada, May 8-11, 2000.
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:
CE is rarely used for routine environmental analysis of organic pollutants -- certainly not to the extent of gas chromatography or high pressure liquid chromatography. There are advantages to CE, however, that belie this lack of application. For example, CE is preferred over GC for ionic organic analytes, even if the pH has to be adjusted to accommodate the analyte pKa, because no derivatization is required. This is especially true for ionic analytes with aromatic or other types of chromophores that absorb readily in the UV, but can be true even when indirect detection has to be used for adequate sensitivity. In addition, CE may be the preferred technique for any chiral analyte, even neutral ones, when enantiomers are to be separated and measured because of the facility with which chiral selectors can be used in CE. These advantages can be negated, of course, when sensitivity is an issue. However, for studies of pollutant fate in laboratory systems, CE with UV detection generally provides adequate sensitivity. Our laboratory has applied CE to enantiomeric separations of ionic and neutral chiral analytes in a routine mode for several years with the object of measuring enantiomeric ratios and respective enantiomer degradation rates in environmental matrices. Examples to be shown include the microbial transformation of.- 1) bromochloroacetic acid, a chiral drinking water disinfection byproduct, in surface waters; 2) ruelene (crufomate), a neutral organophosphorus pesticide, in soil-water matrices; and 3) dichlorprop, a phenoxyacid herbicide, in soil-water matrices. Enantioselectivity was observed in most of these cases; for BCAA the same enantiomer always degraded preferentially, but for ruelene and dichlorprop, enantiomer preference depended upon the characteristics of the matrix.