Determination of insecticides malathion and lambda-cyhalothrin residues in zucchini by gas chromatography

Publication date: December 2013 Source:Bulletin of Faculty of Pharmacy, Cairo University, Volume 51, Issue 2 Author(s): Hayam M. Lofty , Abd El-Aziz A. Abd El-Aleem , Hany H. Monir A sensitive gas chromatographic method has been developed for the determination of malathion and lambda-cyhalothrin (λ-cyhalothrin) insecticide residues in zucchini. The developed method consists of extraction with acetone, purification and partitioning with methylene chloride, column chromatographic clean-up, and finally capillary gas chromatographic determination of the insecticides. The recoveries of method were greater than 90% and limit of determination was 0.001ppm for both insecticides. The method was applied to determine residues and the rate of disappearance of malathion and λ-cyhalothrin from fruits of zucchini (open field treatment, 50cc of Malason/Cormandel 57% EC (emulsifiable concentrate) for 100L of water, 20cc of LAMBDA SUPER FOG 5% liquid for 100L of water). The insecticide incorporated into the plants decreased rapidly with a half-life time around 0.77day (18.5h) for malathion and 4days for λ-cyhalothrin. It is not recommended to use zucchini before 12h of malathion application. For λ-cyhalothrin, the preharvest interval is 5days. Four market samples were chosen from different regions from A.R.E. and all of them showed no residues of malathion or λ-cyhalothrin.
Source: Bulletin of Faculty of Pharmacy, Cairo University - Category: Drugs & Pharmacology Source Type: research