Development of Immunoassays for Type II Synthetic Pyrethroids. 2. Assay Specificity and Application to Water, Soil,...

Cross-reactions of a panel of immunoassays developed for type II (alpha-cyano-) synthetic pyrethroids were evaluated with type I and II compounds. Cross-reactions of both groups were affected by alkali treatment. The treatment typically increased sensitivities of type II compounds, and decreased cross-reactions of type I compounds. After isomerization, each of the 12 combinations studied provided more sensitive detection of deltamethrin than the other compounds, even in the case of antisera and enzyme conjugates based on cypermethrin, cyhalothrin, or their fragments. Several immunoassays were selective for deltamethrin. Assays with the broadest specificities detected type I and II compounds with IC(50) values of 20-400 µg/L. None of the assays detected compounds lacking a cyclopropane ring (fenvalerate, fluvalinate). Spike and recovery studies for deltamethrin in water, soil, and wheat grain indicated that the selected immunoassays quantified it with high precision and good recoveries. Good correlations between immunoassay and gas chromatography/mass spectrometry data were also obtained for incurred residues of deltamethrin and bifenthrin extracts of water and soil samples.