USE OF EXTRACTION DISKS FOR TRACE ENRICHMENT OF VARIOUS PESTICIDES FROM RIVER WATER AND SIMULATED SEAWATER SAMPLES FOLLOWED BY LIQUID-CHROMATOGRAPHY RAPID-SCANNING UV VISIBLE AND THERMOSPRAY MASS-SPECTROMETRY DETECTION

C18 Empore extraction disks were used for the isolation and trace enrichment of several pesticides [chlorotriazines (atrazine, simazine, and cyanazine), the atrazine metabolites (deethyl- and deisopropylatrazine), organophosphorus (parathion-ethyl, fenitrothion, fenamiphos, and tetra-chlorvinphos), phenylurea (linuron), propioanilide (propanil), and carbamate (carbaryl)] from river water and simulated seawater, at concentration levels of 0.25, 25, and 1000 mug/L. The extraction disks allowed relatively high flow rates; thus 1- (for 1000 mug/L) and 4-L (for 25 and 0.25 mug/L) samples could be processed within 30 and 120 min, respectively. For most of the pesticides the recoveries, as determined by liquid chromatography with rapid-scanning UV-visible spectrometry, varied from 80 to 125% whereas for the atrazine metabolites the recoveries varied from 3 to 17%. The limits of detection (LOD) were 0.02-0.01 mug/L. Thermospray liquid chromatography-mass spectrometry in the positive and negative ion modes and filament on has been used for the unequivocal identification of various pesticides following solid-phase extraction. The LOD varied between 2 and 20 mug/L.