Enantiomeric ratios and concentrations of organochlorine pesticides in Ohio soils

Abstract

Past research has shown that selective enzymatic degradation of enantiomers by microorganisms does occur. This work was done to determine the enantiomeric ratios and concentrations of several chiral organochlorine pesticides in soils from across Ohio. Quantitative analysis was done using gas chromatography with electron capture detection using a DB-5 column. Concentrations were determined for nine compounds (o,p'-DDT, p,p'-DDT, p,p'-DDD, p,p'-DDE, cis-chlordane, trans-chlordane, heptachlor epoxide, dieldrin and trans-nonachlor) in eleven agricultural soils and one garden soil. The components of DDT were the only compounds present in all soils analyzed. The garden soil concentration values were similar to those for the agricultural soils. Enantiomeric analysis was done using gas chromatography-mass spectrometry with chiral-phase capillary columns. Enantiomeric excesses were found for five compounds: o,p'-DDT, cis-chlordane, trans-chlordane, oxychlordane and heptachlor epoxide. The largest excesses were seen for heptachlor epoxide. The garden soil showed enantiomeric differences for trans-chlordane, cis-chlordane and heptachlor epoxide.