INTERLABORATORY PROGRAM FOR THE QUALITY-CONTROL OF NITRATE DETERMINATION IN FRESH-WATER

Analyses of freshwaters and groundwaters are routinely performed to monitor the level of contamination by, e.g., nitrates. To verify the quality of such determinations, the Community Bureau of Reference (BCR) has organised an interlaboratory exercise which allowed to identify most of the pitfalls observed in the determination of nitrate at three levels of concentrations (0.5, 8 and 53 mg kg 1). In addition, this first step enabled the BCR to study the feasibility of the preparation of candidate certified reference materials (CRMs) for the determination of nitrate in freshwater. The materials used in this exercise were carefully prepared and their homogeneity and stability were verified by using a flow-injection analysis technique developed for this purpose. This paper presents the main results of the intercomparison.