The n-octanol/water partition coefficient (Pow) was determined for nine pyrethroids. The slow-stirring method is preferred for highly lipophilic molecules as it reduces formation of micro-droplets of n-octanol in the water phase, thereby minimizing overestimation of aqueous concentrations. Triplicate measurements were made with each compound. Test and QC samples were analyzed by GC/ECD or GC/MSD-NCI utilizing corresponding d6 internal standards. The resulting Pow values are as follows; Bifenthrin 7.48, Deltamethrin 6.99, Fenpropathrin 6.40, Lambda-cyhalothrin 7.06, Permethrin 7.08, Cyfluthrin 6.86, Esfenvalerate 7.17, Cypermethrin 6.81, Tefluthrin 6.55. These results, measured by an optimal technique, indicate close agreement within the pyrethroid class. The new values are all higher than those previously reported, sometimes by a large margin.

Determining the n-octanol/water partitioning coefficient (Pow) of nine pyrethroids by the OECD slow-stirring method

248th National Meeting (2014)

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