MSc.

The present investigation on “Monitoring and decontamination of pesticide residues in agricultural commodities” was conducted at the Department of Entomology, College of Agriculture, Vellayani during 2011 - 2013. The objectives were to monitor the pesticide residues in agricultural commodities like rice, wheat, rice flour, wheat flour (atta and maida), cardamom, cumin seed, capsicum, okra and curry leaf and to standardize techniques for decontamination.
Multi Residue Methods (MRM) for pesticide residue analysis in rice flour, wheat flour (atta and maida), rice, wheat, cardamom, cumin seed, capsicum, okra and curry leaf were validated by conducting recovery studies. Five important validation parameters viz., limit of detection, linearity, limit of quantification, recovery and repeatability were established.
Data on monitoring of pesticide residues in agricultural commodity revealed that none of the rice flour, atta, maida, raw rice and parboiled rice samples showed the presence of pesticide residues. However, all the cardamom, cumin seed and curry leaf samples showed presence of multiple pesticide residues at varying levels. Basmathi rice (5 samples), wheat (5 samples), capsicum (3 samples) and okra (2 samples) showed the presence of pesticide residues.
Based on the monitoring data, six insecticides viz., malathion, methyl parathion, chlorpyriphos, quinalphos, cypermethrin and fenvalerate were selected for assessing the effect of washing, soaking and cooking on the removal of insecticide residues in rice and washing, drying and milling on the removal of insecticide residues in wheat at five hours and two weeks after insecticide spraying. Out of different processing techniques studied, four washings in tap water for two minutes along with rubbing of grains followed by cooking removed maximum amount of residues (88.36 - 98.63 %) and four washings in tap water for two minutes along with rubbing of grains removed maximum amount of residues (51.09 - 75.67 %) in wheat.
In order to assess the effect of decortication on removal of insecticide residues, cardamom samples with presence of more than one insecticide were subjected to decortication. It may be seen that most of the detected residues remained on the surface of capsule cover and highly systemic insecticides like profenophos had penetrated into the seed.
In order to standardize a decontaminating solution of household product an experiment was conducted with seven treatments and three replications. Among the decontamination methods adopted to reduce the insecticide residues in vegetables, dipping in 2 % tamarind for 15 minutes was the best treatment to eliminate residues from okra (37.28 - 80.37 %) and curry leaf (38.70 - 98.05 %) whereas dipping in 2 % vinegar solution was the best for decontaminating capsicum (31.18 - 74.88 %). It may be concluded that the efficiency of decontaminating treatments depend on the chemistry of pesticide molecule, age of the pesticide residue and the surface character of the commodity.