ANALYSIS OF ANIONS IN NATURAL-WATERS - A COMPARISON OF METHODS INCLUDING IONCHROMATOGRAPHY AND CONTINUOUS-FLOW-TECHNICS

Using waters from different compartments of forest ecosystems, standard solutions, moreover samples containing known internal standards, several analytical methods were tested for the comparability of nitrate, sulfate and chloride results in an inter-laboratory study. The analytical instruments were ion chromatographs with and without suppression as well as continuous-flow-analyzers. A cluster analysis showed a strong correlation between the obtained data and the analytical method used for nitrate, and a poorer relation for sulfate. Concerning nitrate-analysis, the IC-systems showed a better detection limit and a higher recovery of standards. Mean standard deviation among all tested analytical methods was calculated to be 15 % for nitrate, 10 % for sulfate and 14 % for chloride. These results represent deviations as they may occur during laboratory routine analyses with a high amount of samples and the need for simultaneous determination of several anions. For the examined anions no significant correlation was obtained between the variation of the analytical results and the dissolved organic carbon concentrations of the samples.