TESTING OF MEMBRANE EXTRACTION DISKS FOR ANALYSIS OF 18 PESTICIDES INMARSH WATER SAMPLES BY GC MS/

The development of an analytical procedure in suitable for use in inve stigating the distribution of Alachlor, Atrazine, Chlorpyrifos, Cyanaz ine, Cypermethrin, Diphenamid, Alpha-Endosulfan, Beta-Endosulfan, Fens ulfothion, Fonofos, Methidathion, Metolachlor, Metribuzin, Pebulate, P hosmet, Simazine, Terbufos and Trifluralin in marsh water is reported. The procedure involves a solid-phase extraction of the pesticides usi ng 90 mm C18 disks. Quantitative determination of the pesticides was c arried out by capillary gas chromatography with mass spectrometry dete ction in the SIM mode. Recovery at low mu g/L levels was tested by ext raction of spiked distilled water using either negative (vacuum) or po sitive pressure. The detection limit was 0.05 ng/L for trifluralin and 2 ng/L for the other compounds based on a 10 L water sample. The meth od was compared with liquid-liquid extraction using the Goulden Large Sample Extractor.