Laboratory studies on the effect of refining of groundnut oil on sumithion residues

Oil was extracted from groundnut (Arachis hypogaea) seeds sprayed with sumithion at 5, 10 and 20 mg/kg. The effect of refining stages of groundnut oil (neutralization, bleaching, acid deodorization) in the laboratory on the sumithion (O,O-dimethyl-O- (3-methyl-4-nitrophenyl) phosphorothioate) content of groundnut oil was studied. The loss of sumithion during oil neutralization was 2.5%, which increased on bleaching to 22.5% and steam distillation to 75%.