Assessment Of Selected Pesticide Residue Levels In Some Vegetables Grown Through Irrigation By Small Scale Farmers In Dugda District Of Oromia Region, Ethiopia

Abstract

Two Organochlorines (endosulfan and DDT), four organophosphorus (dimethoate, malathion, diazinon, chlorpyrifos), and one pyrethroid (deltamethrin), pesticide residues were extracted with ethyl acetate followed by ethyl acetate: n-hexane in the order of (90:10 mL v/v) and (80/20 mL v/v) from tomato and cabbage samples and analyzed by Gas chromatography coupled with flam ionization detector. The analysis was carried out by split injections using capillary column GC-FID in Adami Tulu Pesticide Processing Share Company. The vegetable samples were collected from Dugda Woreda, specific areas called Wolda-Kelina and Shubi-Gemo agricultural sites near Lake Ziway. Linearity for determination of these pesticides from tomato and cabbage samples were evaluated using the external calibration curves of each pesticide at five calibration points (0.25, 0.5, 1.25, 2.5 and 5) µg/mL. However in the analysis, organochlorine pesticides (endosulfan and DDT) and chlorpyrifos from organophosphorus, were not detected by this method in both tomato and cabbage samples in the above calibration ranges. But three organophosphorus pesticides (dimethoate, diazinon, malathion), and one pyrethroid pesticide (deltamethrine) were detected with residual concentrations of 0.35, 0.22, 0.16 and 0.97µg/g respectively in tomato and 0.16, 0.06, 0.19 and1.67µg/g respectively in cabbage samples. The average recoveries for most of the pesticides were in the acceptable range and the detection limit of each detected pesticide is below MRL.