Determination of organochlorine pesticides in river water using dispersive liquid-liquid microextraction and gas chromatography-electron capture detection

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-electron capture detection (GC-ECD), has been developed for the extraction and determination of 14 organochlorine pesticides (hexachlorocyclohexanes (-HCH, -HCH and -HCH), Lindane (-HCH), Aldrin, Dieldrin, Endrin, Heptachlor, Heptachlor epoxide, -Chlordane, -Chlordane and p,p'-DDT, p,p'-DDD, p,p'-DDE) in river water samples. Factors relevant to the microextraction efficiency, such as the kind of extraction and disperser solvent, their volume and the salt effect was investigated and optimised. In this method the appropriate mixture of extraction solvent (13.5 mu L carbon disulphide) and disperser solvent (0.50 mL acetone) were rapidly injected into the aqueous sample by syringe. The values of the detection limit of the method were in the range of 0.05-0.001 mu g L-1, while the relative standard deviations for five replicates varied from 2.7 to 9.3%. A good linearity (0.9894 r2 0.9998) and a broad linear range (0.01-200 mu g L-1) were obtained. The method exhibited enrichment factors ranging from 647 to 923, at room temperature. The relative standard deviations varied from 2.7 to 9.3% (n = 5). The relative recoveries of each pesticide from water samples at spiking levels of 2.00 and 10.0 mu g L-1 were 88.0-111.0% and 95.8-104.1%, respectively. Finally, the proposed method was successfully utilised for the preconcentration and determination of the organochlorine pesticides in the Jajrood River water samples.