EFFECT OF WASHING ON RESIDUES OF CHLORPYRIFOS AND MONOCROTOPHOS IN VEGETABLES

In this study the effect of washing on residue of chlorpyriphos and monocrotophos in capsicum and cauliflower was determined. The washing processes were carried out with normal and hot water with different span of time. The vegetables samples were washed with normal and hot water (~500C). The samples were extracted with 1% acetic acid in acetonitrile mixture and cleaned up with primary secondary amine (PSA) and magnesium sulphate and analysed by gas chromatography electron capture detection. The chlorpyriphos residue reduced in capsicum and cauliflower from 25 to 42% after normal water washing, and 36-74% reduced with hot water washing. Whereas monocrotophos residue was reduced in capsicum and cauliflower 23 to 39% after normal water washing and 35-72% reduced after hot water washing. The vegetable samples collected from the local market contained detectable residues representing approximate 80% rate of contamination. There were some of the vegetables samples contained chlorpyriphos and monocrotophos residues above maximum residue limits (MRLs). However, washing of vegetable reduced some extent of the pesticide residues. The average recoveries of pesticide residues in cauliflower and capsicum samples are 80.0 to 100.0 %.