Intercomparison 0822: pH, Cond, HCO3, NO3-N, C1, SO4, Ca, Mg, Na, K, Fe, Mn, Cd, Pb, Cu, Ni, and Zn (ICP Waters report 93/2008)

Abstract

76 laboratories received samples for the intercomparison 0822, and 74 laboratories in 29 countries submitted results. Two sample sets were used, one for the determination of major ions, and one for heavy metals. Based on the general target accuracy of 20 %, 69 % of the overall results were considered as acceptable. The best results were reported for the analytical variables sodium, chloride, and calcium, with 91, 85 and 85 % acceptable results, respectively. Low percentage of acceptable results was observed for some heavy metals, for instance copper with 20 % acceptable results. The main reason is the low concentrations of some metals in the samples used. Alkalinity was also a big problem this time, with only 35 % acceptable results. Harmonization of the analytical methods used, and the practical procedures followed, may probably be the most important way to improve the comparability for these parameters.