CHLORPYRIFOS IN BIOLOGICAL SAMPLES BY HPTLC

Chlorpyrifos, an organophosphorous compound, is widely used as an insecticide to improve the yield of agricultural produce in India and world. The present study was conducted to screen biological samples received in forensic science laboratories for residual chlorpyrifos. Detection of chlorpyrifos in viscera is usually done by thin layer chromatography using Hexane: acetone (8: 2) as solvent system. Mercurous nitrate, mercuric nitrate (HgNO3) followed by diphenyl carbazone and mercuric nitrate (HgNO3) followed by potassium ferrocynide (K4Fe (CN) 6) are used as chromogenic reagents. Due to presence of chlorine, the identification was supported by applying flame test. Routinely used solvent system the hexane: acetone (8: 2) separates the compounds at the solvent front and creates confusion in the identification. Various proportions of same solvent system where tried and a good separation of chlorpyrifos was achieved by using 9:1 ratio. The Rf value in this system was found to be 0.75. The system is specifically useful for separating the insecticide in biological samples. In non biological samples 8:2 ratio also serve the purpose. The detection limit for the insecticide in this system is found to be 5 μg.