Report on the intercomparison run IAEA-155 trace elements in whey powder

Analytical results need to be reliable, and analysts are well serviced to test their complete analytical systems, methods, instruments, personnel, data reduction, etc., on a frequent basis. Besides the use of standard reference materials, the intercomparison runs provide an excellent opportunity for the determination of accuracy. By comparing their results with results obtained by different methods of preparation and measurement, the participating laboratories have the opportunity to check their analytical performances. At the same time the IAEA's AQCS can establish the concentration of some elements for certification purposes. The participants were requested to determine as many elements as possible with emphasis on ''essential'' and ''toxic'' elements related to human health and environmental pollution in the intercomparison whey powder sample (IAEA-155) as well as in the control sample IAEA. It was expected that the results for IAEA would improve the evaluation of the intercomparison results of IAEA-155 as the concentrations of some inorganic constituents were well established in the IAEA sample. In total 69 laboratories from 24 different countries participated in this exercise. As a basis for the evaluation, 580 laboratory means were reported comprising 2699 individual results for 45 elements. For 3 additional elements information was supplied that the value was below the detection limits of the methods. Even though information and data on 48 elements were reported for IAEA-155 only 4 elements are assigned Class A and 13 elements Class B recommended values. The elements Mg, Mn, Na and P were assigned ''Class A''. But contrary to some former intercomparison exercises, this time sufficient results could be obtained to set ''Class B'' recommended values for some ''difficult to determine'' elements like Cd, Co, Cr, Hg, Ni, Pb, Se. Figs, 45 tabs