Determination of trace elements in danube water: results of the regional-interlaboratory study

The “1st South-Eastern European Interlaboratory Study WATER ANALYSIS-2003” was organized in the period of November 2003 to February 2004, on the basis of European and international experiences. The total of 38 laboratories took part in “WATER ANALYSIS-2003”. Three laboratories were from Greece, one from the Republic of Srpska — Bosnia and Hercegovina, eight from Romania and all others from Serbia and Montenegro. The task for participants was to determine some or all trace elements (Al, As, Cd, Cu, Mn, Fe, Pb and Zn) in two samples prepared from filtered water of the river Danube near Belgrade. Participants could freely select the analytical methods. Results obtained for the determination of lead and cadmium were presented in this paper. All results were analysed using the same methods as in the interlaboratory studies organized by IRMM-JRC (Institute for Reference Materials and Measurements: EU-Joint Research Centre, Geel, Belgium) within IMEP (International Measurements Evaluation Programme). Reproducibility (R) and repeatability (r) were calculated according to the British standard BS 5497: Part I: 1987 (ISO 5725: 1986). The interlaboratory study was successful and most of laboratories obtained good results. Their achievement was better than in some earlier interlaboratory studies.

20.0 6.2 15.3 25.3 7.9 26.8 Table 2 Results of cadmium and lead determination (µg/L) Sample Lead A Number of results Number of accepted results Median Repeatability (r) Reproducibility (R) Cadmium B 38.2 8.1 39.7 110.0 21.7 76.8 to standard deviations of corresponding results — if values of r and R were smaller the agreement was better. Corresponding values were calculated for determination of cadmium and lead (Table 2). Considerably smaller values obtained for the reproducibility of cadmium (Table 2) indicated that better agreement among laboratories was obtained for this element. It is of interest to compare the results in this regional interlaboratory study with the international interlaboratory study IMEP-9 organized in 1998 by experts of the European Commission — Institute for Reference Material and Measurements [4]. Results of IMEP-9 presented in Table 3 correspond for lead and cadmium determination in water sample for Balkan countries (which are not exactly the same South Eastern European countries, which participated in the regional Regional interlaboratory study, which included determination of eight trace elements in Danube water as the sample matrix, was generally successful and useful for all participants. There was a good agreement between results of most laboratories. The achievement was better than in some earlier interlaboratory studies. Systematic errors were observed in some cases and these laboratories need to improve their performance. Similar regional interlaboratory studies will be organized in the future.