The increasing concern about the quality of our environment has initiated the development of novel analytical strategies allowing the determination of organic micropollutants at the trace levels desired by e.g., E.U. directives. However, the increasing demand for such trace-level analytes and the need to obtain sufficient structural information for unambiguous analyte identification, require a distinct reduction of the time of analysis and a more sophisticated detection. In the present project, analytical systems will be designed and optimized which are based on the on- line combination of membrane-based aqueous sample introduction and rapid narrow-bore gas chromatography (GC) with ion trap-type tandem mass spectrometric (MS/MS) detection. The combined use of powerful MS/MS detection for sensitive and selective identification with rapid (10- 15 min versus conventional 45 min) GC separation will permit a serious reduction of the aqueous sample size from, typically, 10 ml to less than 1 ml. This in its turn will require the design of a novel large-volume-introduction (LVI) module for injection. In other words, a completely redesigned LVI-GC-MS/MS set-up will eventually emerge. Its practicability for the trace-level determination of a variety of organic microcontaminants will be demonstrated for different types of water samples (tap, surface, ground and waste water) and, with minor modifications, for organic extracts obtained with non-aqueous samples. Monitoring and screening studies will deal with organo-sulphur, -phosphorus, -nitrogen, -halogen and -tin compounds, and both target analysis and the identification of unknowns will be pursued. Emphasis will be on microcontaminants typical for polluted regions in Saxony (Germany). Pollution profiles will be compared with those observed in other parts of the European Union.