ONLINE TRACE-LEVEL ENRICHMENT GAS-CHROMATOGRAPHY OF TRIAZINE HERBICIDES, ORGANOPHOSPHORUS PESTICIDES, AND ORGANOSULFUR COMPOUNDS FROM DRINKING AND SURFACE WATERS

A simple, selective and precise procedure for the analysis of water sa mples by on-line solid phase extraction gas chromatography (SPE-GC) is presented. The determination of several triazines, organophosphorus p esticides, sulfur containing compounds in tap water was performed by S PE-GC using polymer-packed precolumns and flame ionization (FID), nitr ogen-phosphorus (NPD) or flame photometric (FPD) detection. A cartridg e packed with silica was inserted between the precolumn and the gas ch romatograph in order to eliminate trace amounts of water present in th e ethyl acetate used as desorption solvent. Incorporation of a drying step allowed the retention gap to be used for the analysis of ca. 100 samples without significant deterioration of the chromatographic peaks . Analyte recovery was at least 72% when 10 ml of tap-water sample wer e analysed. The detection limits for all analytes in tap water were lo wer than 0.1 mu g l(-1), with all detectors used. Although with NPD an d FPD, selectivity and sensitivity were markedly better. The SPE-GC-NP D system has also been used for the analysis of surface-water samples from different European rivers.