Intercomparison 0519: pH, Cond, HCO3, NO3+NO2, C1, SO4, Ca, Mg, Na, K, Fe, Mn, Cd, Pb, Cu, Ni, and Zn (ICP Waters report 82/2005)

Abstract

79 laboratories received samples for the intercomparison 0519, and 75 laboratories in 30 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 %, 73 % of the overall results were considered acceptable when the trace metals cadmium, lead and nickel was excluded from the evaluation. The best results were reported for the analytical variables sodium and sulphate, with 87 and 86 % acceptable results, respectively. Lowest percentage of acceptable results were observed for the heavy metals, especially for lead, cadmium and nickel. The main reason for this result was the very low concentrations of these metals in the samples used this time. Harmonization of the analytical methods used is necessary to improve the comparability for pH.