ABSTRACT
A challenge for the environmental chemist is the development of reliable sampling and analytical procedures for the representative assessment of water quality.1-4 Currently, most water monitoring methods rely on the collection at de ned periods of discrete spot, grab, or bottle samples followed
by instrumental analysis in the laboratory. As many pollutants can be present in the water phase at very low concentrations, the collection of large volumes of water is often needed for analysis. In addition, the analysis of spot water samples provides only a snapshot of the levels of pollutants at the time of sampling. This may not give an accurate assessment of water quality in situations where pollutant concentrations uctuate widely and where episodic pollution events occur. Data from round robin exercises of the analysis of pollutants found in spot water samples showed that there are often recurring problems of interlaboratory reproducibility especially when the pollutants are present in trace concentrations.5 Issues of poor reproducibility are often linked to the procedures used in collecting the water for analysis.
