Determination of Ethofenprox Spreading oil distribution on water surface by HPLC

A method was developed for the determination of Ethofenprox Spreading oil (SO) distribution, a novel Labour-saving formulation using in paddy field, by high performance liquid chromatography (HPLC). The method used a reversed-phase C₁₈ column and methanol-water (90+10, v/v) mobile phase. The quick, easy, cheap, effective, rugged and safe method was used for extraction of Ethofenprox from water surface, which involved the extraction of 1.55 μL sample homogeneous distribution with 10 mL water, followed by the covering of oil-absorbing paper (OAP). After twenty minutes, Ethofenprox was extracted into OAP. Then, the paper was shaked in 10 mL methanol. After concentration, the final extract was transferred to an autosampler vial for concurrent analysis by HPLC. Etofenprox in a good linear relationship in the ranges was studied, 0.1-20.0 mg L^-1, with high correlation coefficients (0.9999). The RSDs were 0.12%. The average recoveries of Ethofenprox fortified at different levels were within 90.9-96.5%, and the precision of the test method was 1.6-4.4%. The proposed method was successfully applied to determine Ethofenprox distribution on water surface.