Determination of organochlorine pesticides in marine sediments samples using ultrasonic solvent extraction followed by GC/ECD

A rapid multiresidue method has been developed for the analysis of 17 organochlorine pesticides (OCPs) (alpha-HCH, gamma-HCH, beta-HCH, delta-HCH, aldrin, heptachlor epoxide, endosulfan 1, 4,4-DDE, dieldrin, endrin, 4,4-DDD, endosulfan 11, 4,4-DDT, endrin aldehyde, endosulfan sulfate, methoxychlor and endrin ketone) in marine sediments. The method is based on the ultrasonic solvent extraction (USE) of sediment samples. The extraction procedure was optimised with regard to the solvent type, amount of solvent and duration of sonication steps. Analytical determinations of the 17 OCPs were carried out by gas chromatography using electron capture detector (GC/ECD). The highest recoveries from sediment samples spiked at trace concentrations of 50 ng g(-1)obtained when samples were extracted two times by ultrasonication for 20 min with 5 mL of dichloromethane. Recovery studies were performed at 1, 2, 5, 10 and 50 ng g(-1) fortification levels and correlation coefficients obtained ranged from 0.9652 to 0.9993 showing that the method is linear over the range assayed. The detection limits (signal/noise = 3) for the organochlorine compounds tested in marine sediments varied from 0.1 to 1 ng g(-1) dry weight. USE of OCPs from marine sediments using dichloromethane showed satisfactory extraction efficiencies combined with simplicity of use and low solvent consumption.