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 anal yses of 17 organochlorine pesticides in sediments employing microwave assisted extraction followed by gas chromatographic separation with ma ss spectrometric detection using a computer optimized temperature prog ram. For optimization, 5 g portions of sediment were spiked with a sta ndard solution of the 17 analytes in isooctane at similar to 50 ng/g f or 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 a nd 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 al l analytes and MDLs were in the range from 2-9 ng/g. To show the envir onmental applicability, the method was employed for the analysis of na turally contaminated sediments from the Netherlands (SETOC 701). The r esults were compared with the results obtained in our lab with ultraso nic extraction and supercritical fluid extraction and corresponded wel l with the median of results obtained from different interlaboratory c omparison studies.