HBM4EU ICI EQUAS report Chromium in urine round 1

Within the framework of the HBM4EU project, an Inter-Laboratory Comparison Investigation (ICI) was organized and conducted for the analysis of chromium (Cr) in human urine. The study was performed from August 2018 to September 2018. In total, 10 laboratories from 8 countries participated in this ICI. The participation in the ICI was satisfactory, as 10 out of 10 laboratories submitted their results. Six test samples consisting of 2.2 mL urine each were prepared, corresponding to different concentration levels of the targeted biomarker, and sent to the participating laboratories for analysis. These samples were defined as follows: – 3 samples at low Cr concentration, to be below or as close as possible to expected instrumental detection limits. – 3 samples at high Cr concentration. Homogeneity and stability assessment of the material confirmed that low and high Cr concentration level samples were adequately homogeneous and stable. Laboratory results were rated using z-scores in accordance with ISO 13528 and ISO 17043. The default standard deviation applied for proficiency assessment (i.e. target standard deviation) was set to FFP = 25 %. Assessment scores were calculated for high and low concentration level samples. As a global overview, the proportion of satisfying results (-2 < Z-score < 2) was 100 %.