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 Measurements' International Measurement Evaluation Programme, 277 clinical laboratories from 17 countries participated. The measurands consisted of inorganic components, present at minor and trace level, in a human liquid serum. Results 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 conclusion is that routine measurements of total concentrations of the components by clinical laboratories are of high quality. The fraction of significant errors is small (0.5%) and the self-declared uncertainty values are generally fairly realistic. Results are further commented on with respect to the recent development in metrology in chemistry.