A SIMPLE METHOD FOR SOLID-PHASE EXTRACTION OF MALATHION IN WHEAT FLOUR

Malathion is a widely used organophosphorus (op) insecticide which its residue in food stuffs must be detected continuously. a simple method of solid-phase extraction (spe) and further thin layer chromatography (tlc) for extraction and detection of malathion in wheat flour is introduced, briefly, flour samples were mixed with various concentrations of malathion and 1 m potassium phosphate buffer (ph=6.0), and washed with methanol. methanolic extracts were divided into 3 equal volumes and each volume was separately poured in spe columns and eluted with 3 different solvents. eluates were evaporated under a steam of nitrogen at room temperature. extracts were reconstituted in 100 ml of solvents and 10 ml of them were spotted on tlc plates. after development of tlc plates, they were sprayed with palladium chloride reagent evenly. the spots were evaluated visually and spectrophotometrically. results showed that spe with methanol has the highest recovery.regarding importance of measuring malathion, the present method can be used by many reference laboratories for detection of malathion residue in food stuff.