Organochlorine pesticides assessment in sediment samples from vaal river by accelerated solvent extraction technique

Abstract

The excessive use of pesticides has become a global concern owing to the great adverse effect exerted on human health and the environment. The application of Soxhlet extraction (SE) and accelerated solvent extraction (ASE) techniques to the analysis of 15 organochlorine pesticides (OCPs) in sediment samples was described. Sediment samples were obtained from the Vaal River, the largest tributary of the Orange River in South Africa. The method detection limit (MDL) is in the range of 0.01 to 0.25 mg/L, and the average recoveries were in the range 63.2 %-96.0% with standard deviations in the range 3 %-12.5 %. The total OCPs are in the values of 0.352 µg/L, 0.352 µg/L, and 0.212 µg/L in the sediments from Vereeniging, Barrage, and Parys respectively using the ASE method. Higher values of 4,4ʹ-DDE, 4,4ʹ-DDD, and 4,4ʹ-DDT were found in samples collected from Vereeniging and Barrage locations within the range 0.068-0.095 µg/L and 0.063-0.089 µg/L respectively. The mean concentrations of OCPs residues in the sediment samples follows the order: endosulfan I > 4,4ʹ-DDT > 4,4ʹ-DDE > 4,4ʹ-DDD > α-HCH > β-HCH > heptachlor epoxide > trans-chlordane > γ-HCH heptachlor. It was revealed that the ASE was the optimal technique for the analysis of OCPs in sediments. It can be concluded that the accelerated solvent extraction (ASE) is an effective extraction technique for the analysis of organochlorine pesticides from sediment matrices within a short period, and consumes less solvent.