Evaluation of an automated solid-phase extraction system for the enrichment of organochlorine pesticides from waters

An automatic method for the determination of organochlorine pesticides (OCPs) in water samples was developed. The analytes are preconcentrated onto a customized RP-C18 column and subsequently eluted with 80 μl of ethyl acetate. Gas chromatography with electron capture detection is used for their separation and selective detection. Detection limits for 10 ml sample volumes range from 0.01 to 0.1 ng ml−1, with standard deviations between 4 and 6%. The average recovery at a fortification level of 2 ng ml−1 is 92%. The method was used to screen OCPs in natural waters collected near agricultural areas and also to tap waters. Positive findings were confirmed by gas chromatography with mass spectrometric detection. Finally, the adsorption/degradation of OCPs in natural pond water containing a high level of suspended matter was examined; some OCPs were found to be degraded and irreversibly adsorbed on suspended matter present in the water.