Simple, specific analysis of organophosphorus and carbamate pesticides in sediments using column extraction and gas chromatography

A simple, specific procedure was developed for the analysis of organophosphorus and carbamate pesticides in sediment. The wet soil was mixed with anhydrous sodium sulfate to bind water and the residues were column extracted in acetonermethylene chloride (1:1, v/v). Coextracted water was removed by additional sodium sulfate packed below the sample mixture. The eluate was concentrated and analyzed directly by capillary gas chromatography using phosphorus and nitrogen specific detectors. Recoveries averaged 93% for sediments extracted shortly after spiking, but decreased significantly as the samples aged.