Multiresidue procedures for determination of triazine and organophosphoruspesticides in water by use of large-volume PTV injection in gas chromatography

Two procedures, based on large-volume injection with a programmed-temperatu re vaporizer (PTV), have been developed for the determination of several tr iazine and organophosphorus pesticides. The use of PTV for injection in gas chromatography (GC) has enabled the introduction of up to 200 mu L sample extract into the GC, thus increasing the sensitivity of the method. PTV inj ection has been combined off-line with two different microextraction proced ures - liquid-liquid partition and solid-phase extraction. A simple and rapid off-line liquid-liquid microextraction procedure (5 mL w ater/1 mt methyl tert-butyl ether) was applied to surface water samples spi ked at levels between 0.01 and 5 mu g L-1. Recoveries of the overall proced ure were >80 % and the precision was better than 15 %. Detection limits wer e <30 ng L-1 from 200-mu L injections in GC-NPD analysis of triazines and G C-FPD analysis of organophosphorus pesticides. Off-line automated solid-pha se extraction with C-18 cartridges has been applied to water samples (50 mL ) spilled at 0.01, 0.1 and 1 mu g L-1 The overall procedure was satisfactor y (recoveries >80 % and coefficients of variation <12%) and the limits of d etection ranged from 1 to 9 ngL(-1). Finally, several surface water samples were analysed, and triazine herbicid es were detected at concentrations of approx. 0.1-0.2 mu g L-1. The results were similar to those obtained by conventional solvent extraction then GC- MSD after splitless injection of 2 mu L.