GAS-CHROMATOGRAPHIC WATER ANALYSIS BY DIRECT-INJECTION OF LARGE-SAMPLE VOLUMES IN AN ADSORBENT-PACKED PTV INJECTOR

A GC method is described for the determination of pollutants in aqueous samples by direct enrichment out of large sample volumes in a PTV injector. The vaporized water is eliminated through the split vent and the analytes are concentrated on an adsorbent inside the insert of the PTV. For the selection of suitable adsorbents, breakthrough volumes of selected pesticides and nitroaromatics on Tenax TA, Tenax GR, Chemipack C18 and graphitized carbon blacks have been determined by experiment. The determination of the breakthrough volumes was carried out directly in the PTV insert. Tenax TA proved to be the best sorbent with regard to the breakthrough volumes and its inertness to the analytes to be determined. As the result of the investigations, 500 mu l of aqueous standard solutions of pesticides and nitroaromatics (concn. = 0.02 ... 2 mu g/l) were analyzed with an average relative standard deviation of 10 %. The procedure was successfully applied for the analysis of real samples.