Ion Analysis at the Highest Stage ? The Metrological Approach by National Metrological Institutes

Abstract

National Metrological Institutes (NMI's) from fifteen different countries participated in interlaboratory comparisons where concentrations of about 1 g kg À1 in solutions of aluminium, copper, iron, magnesium, chloride and phosphate were measured. A very high comparability of the results irrespective of the analyte and the applied measurement technique was observed. The relative in-between laboratory standard deviations of the results as reported by the participating laboratories were between 0.13% for copper and chloride up to 0.33% for aluminium, and all of the 81 results were found in the range of AE1% with respect to the reference value. Due to the gravimetric preparation of the samples, a conventional true reference value was calculated, and no significant deviations of the reference values and the means of all results reported by the institutes were found.

High Precision Titrimetry, Ion Chromatography and ICP-Optical Emission Spectrometry for the Estimation of Inhomogeneities in Aqueous Calibration Solutions for Metrological Purposes

“…The comparability of the NMI's results for such intercomparison studies with calibration solutions was very good, and deviation from the reference value of most results was less than 0.1% rel. [5]. Therefore it is of particular importance to know the exact value and uncertainty of the mass fraction of the analyte in these intercomparison samples provided by the piloting NMI.…”