AGRO 52 |
| The purpose of this study was to determine a rigorous extraction technique and analytical method for the analysis of sediment-bound pyrethroid pesticides and to examine partitioning and isomerization of the pyrethroid λ-cyhalothrin in an aqueous-sediment system. Method development compared sonication with soxhlet extraction and optimized GC-ECD analysis. To investigate partitioning and isomerization, reactors containing sediment and water were fortified with λ-cyhalothrin and extracted at time points ranging from 20 min to 28 days after fortification. The transformation of the enantiomeric pair contained in pure λ-cyhalothrin to a mixture of two cis enantiomeric pairs was observed and quantified in both the aqueous and solid phases. Isomerization of the aqueous and solid phase cyhalothrin reached steady state after 21 days of contact. Racemization of the aqueous phase λ-cyhalothrin occurred, whereas in the solid phase, only 35% of the λ-cyhalothrin isomerized. Isomerization in the solid-phase cyhalothrin was likely inhibited because it was sorbed. |
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Synthetic Pyrethroids and Surface Water Quality
8:30 AM-11:20 AM, Monday, 11 September 2006 San Francisco Marriott -- Salon 3, Oral
Division of Agrochemicals |