Last Updated: 17-10-2019 11:27
Within the framework of the HBM4EU project, an External Quality Assurance Scheme (EQUAS) was organized and conducted for the analysis of Polycyclic Aromatic Hydrocarbon metabolites (PAH met.). PAH met. correspond to eleven biomarkers: 1-naphthol, 2-naphthol, 2-FLUO, 3-FLUO, 9-FLUO, 1-PHEN, 2-PHEN, 3-PHEN, 4-PHEN, 9-PHEN and 1-PYR in urine.
The study was performed from May 2019 to July 2019.
In total, 40 laboratories were invited for this 2nd EQUAS/round 3, of which 25 laboratories from ten countries registered.
The participation in this EQUAS was satisfactory; 25 out of the registered 25 laboratories (100%) submitted their results.
In June 2019, twelve different test samples consisting of 5 mL urine spiked with PAH met. at two different concentrations (PAH met.low and PAH met.high), six of each concentration, were prepared and sent (on dry ice) to the participating expert laboratories for single analysis. Each candidate laboratory got two samples, one of each concentration for single analysis.
The HBM4EU QAU had selected six expert laboratories for PAH met. in urine. Four expert laboratories were from Europe (HBM4EU consortium) and also participated as candidates. Two expert laboratories were from outside Europe (Japan, USA).
Homogeneity assessment of the control materials confirmed that the materials were adequately homogeneous (except 9-PHEN low level). The stability test demonstrated no significant loss of the biomarkers in the course of this EQUAS.
The proficiency of the laboratories was assessed through Z-scores, which were calculated using the mean concentration as established by expert laboratories as assigned value, and a fixed fit-for purpose relative target standard deviation (FFP-RSDR) of 25%. Assigned values and Z-scores could be determined for nine biomarkers at the low level and for nine biomarkers at the high level.
For two biomarkers (4-PHEN, 1-PYR), Z-scores could only be determined using the consensus value of the ICI as described in SOP HBM4EU-SOP-QA-003.
The percentage of satisfactory Z-scores obtained for each biomarker ranges from 60% (3-FLUOlow) to 100% (4-PHENhigh).
For two biomarkers (9-FLUO, 9-PHEN) no kind of Z-score could be provided.