Microwave assisted extraction of organochlorine pesticides from sediments and its application to contaminated sediment samples

A method was established and optimized for rapid and reproducible analyses of 17 organochlorine pesticides in sediments employing microwave assisted extraction followed by gas chromatographic separation with mass spectrometric detection using a computer optimized temperature program. For optimization, 5 g portions of sediment were spiked with a standard solution of the 17 analytes in isooctane at similar to 50 ng/g for each pesticide and extracted in a microwave oven for 30 min at 100 degrees C using three different solvents. The best recoveries between 74% and 99% (RSD = 1.0-10.2%) were obtained with tetrahydrofuran. The time consuming and laborious clean-up using liquid/liquid-extraction and two column-chromatographic steps was replaced by a one step liquid/solid-extraction, showing the same or even better performance in terms of recovery and reproducibility. Calibration plots were linear for all analytes and MDLs were in the range from 2-9 ng/g. To show the environmental applicability, the method was employed for the analysis of naturally contaminated sediments from the Netherlands (SETOC 701). The results were compared with the results obtained in our lab with ultrasonic extraction and supercritical fluid extraction and corresponded well with the median of results obtained from different interlaboratory comparison studies.