Development of Validated Method Using QuEChERS Technique for Organochlorine Pesticide Residues in Vegetable

A simple method was evaluated for the determination of 18 pesticide residues (alpha-BHC, betha-BHC, gamma-BHC, delta-BHC, Heptachlor, Aldrin, α-Endosulfan, DDE, Dieldrin, Endrin , β-Endosulfan, DDD, Endrin Aldehid, Endosulfan Sulfat, DDT, Endrin Keton and Metoxychlor) in lettuce where pesticide residues were extracted and cleaned using a buffered QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method, followed by GC-MS analysis. This extraction method involves first mixing the sample with acetonitrile and permit the salt out liquid-liquid partitioning step using anhydrous MgSO₄ and sodium acetate. After shaking and centrifugation, cleanup is done by dispersive solid phase extraction (d-SPE) using 150 mg of anhydrous MgSO₄, 150 mg of PSA, and 50 mg of C-18 per milliiter of extract. The optimized analytical conditions were evaluated in terms of recoveries, repeatability, limits of quantitation and matrix effects for lettuce sample. Use of matrix matched standards provided acceptable results for most pesticides with overall average recoveries between 70 and 120% and consistent RSD < 15% for organochlorine pesticides.