Determination of Pesticide Residue in Water and Khat (Catha edulis) Leaves Using GC-ECD

In this work the concentration of some selected pesticides such as aldrin, dialdrin, BHC, diazinon, DDT, 4,4-DDE and heptachlor were investigated in water and khat samples that were collected from five different sites. The pesticides were extracted using liquid-liquid and solid phase extraction technique and analyzed by GC-ECD. The recovery test, linearity cure and extraction efficiency were tested by using standard pesticide samples. The highest concentration of pesticide obtained in water samples is diazinon in WS 2 (0.0698mg/L), and the lowest concentration is heptachlor in WS 3 (0.0006mg/L). The highest and lowest concentrations of pesticides obtained in Khat samples are diazinon in KS 1 (0.0323mg/L) and KS 3 (0.0001mg/L) respectively. The concentration of diazinon and four isomers of BHC detected in each water sample are higher than the recommended limits set by WHO which shows contamination of the lake water. Diazinon and DDT levels in KS 1 (0.0323mg/L), KS 2 (0.0293mg/L) and KS1 (0.0134mg/L), KS 2 (0.0173mg/L) respectively are above the maximum residue level. Keywords: concentration, DDT, diazinon, extraction, heptachlor DOI : 10.7176/CMR/11-3-03 Publication date :March 31 st 2019