Abstract: Gas chromatography (GC) coupled with dual columns and dual electron capture detectors (ECD) was established to determine 23 organochlorine pesticides in 5 soil and 5 sediment samples. Microwave assisted extraction and solid phase extraction with a Florisil column and sulfur cleanup with copper powder were used in sample pre-processing. Chromatographic analysis was performed on DB-XLB and DB-1701 capillary columns by internal standard method. This method showed good extraction efficiency, high sensitivity and good reproducibility. In the same linear range of 0.005~0.5 mg/L of 23 pesticides, the correlation coefficients were higher than 0.997. The average spiked recoveries were 50%~119% with the relative standard deviations (RSDs) of 0.9%~16.1% (n=6) in 5 soil samples, and were 52%~120% with RSDs of 0.3%~28.4% (n=6) in 5 sediment samples, respectively. The detection limits were 0.00005~0.0005 mg/kg. The results indicate that this method is suitable for the determination of the 23 organochlorine pesticides in soil and sediment samples.

Key words: organochlorine pesticides, sediment, soil, gas chromatography coupled with dual columns and dual electron capture detectors, microwave extraction