SCREENING OF ORGANOPHOSPHORUS PESTICIDES IN ENVIRONMENTAL MATRICES BY VARIOUS GAS-CHROMATOGRAPHIC TECHNIQUES

Gas chromatography with nitrogen-phosphorus detection (GC-NPD) using three different capillary columns, DB-1701, RSL-300 and DB-5, was employed for the identification of 25 organophosphorus pesticides and various transformation products. Spectral information on and typical fragment ions of the different compounds were obtained by gas chromatography-mass spectrometry with electron impact and negative-ion chemical ionization. Clean-up methods involving Florisil, Empore C18 extraction discs, C18 cartridges and gel permeation chromatography using Bio-Beads S-X3 were evaluated for the isolation of selected organophosphorus pesticides from water and biota samples. Recoveries for water samples varied from 77 to 120% with a relative standard deviation of 2-8% whereas recoveries of 30-130% were obtained with biota samples. Applications are reported for the determination of pyridafenthion in water samples from the Ebro delta (Tarragona, Spain).