Priority substances of the European Water Framework Directive: analytical challenges in monitoring water quality

To ensure the production of valid, comparable data for implementing the European Water Framework Directive, it appears necessary to develop internationally validated reference methods for priority pollutants and to organize inter-laboratory exercises. This paper gives an overview of the work needed for the analysis of priority substances. The assessment of the results of four years of inter-laboratory testing (1999-2002) for the analyses of chemical contaminants in water has shown that future intercomparison campaigns should focus on organic substances that seem to be the most problematic.