The IRMM International Measurement Evaluation Programme (IMEP) IMEP-7: Inorganic components in human serum

In the seventh round of the Institute for Reference Materials and Measureme nts' International Measurement Evaluation Programme, 277 clinical laborator ies from 17 countries participated. The measurands consisted of inorganic c omponents, present at minor and trace level, in a human liquid serum. Resul ts for calcium, chloride, copper, magnesium, sodium, selenium and zinc are reported and are compared to reference values established mainly by isotope dilution mass spectrometry and neutron-activation analysis. The overall co nclusion is that routine measurements of total concentrations of the compon ents by clinical laboratories are of high quality. The fraction of signific ant errors is small (0.5%) and the self-declared uncertainty values are gen erally fairly realistic. Results are further commented on with respect to t he recent development in metrology in chemistry.