Last Updated: 19-10-2020 15:52
Within the framework of the HBM4EU project, a 2nd interlaboratory comparison was organised for the determination of nine pesticide biomarkers in urine. Included were biomarkers for glyphosate and AMPA (glyphosate and AMPA), chlorpyrifos (TCPy), and pyrethroids (3-PBA, 4-F-3-PBA, cisDBCA, cis-DCCA, trans-DCCA, and ClF3CA).
The study was performed in February/March 2020 and was conducted to assess the comparability and reliability of analytical methods across the participating expert laboratories.
The HBM4EU QAU had selected four expert laboratories for pesticide biomarkers in urine. The expert laboratories were from four different countries in Europe. For glyphosate/AMPA, two additional laboratories analysed the samples (the lab preparing the control material, and an external laboratory).
Each participant received two control materials of human urine to be analysed for glyphosate and AMPA (present at 0.4-1.9 ng/ml), and two other control materials, which both contained the chlorpyrifos biomarker (0.6-3.6 ng/ml) and pyrethroid biomarkers (0.1-1.4 ng/ml). The laboratories were requested to perform a single analysis and the submit results to the organiser within 3-4 weeks.
A first assessment of comparability of results was done by calculation of the mean, the RSD, and the relative uncertainty of the mean. Results were compared against the mean through a Z-score when the relative uncertainty of the mean was within 17.5%. In case the relative uncertainty exceeded this value, no objective reliable quantitative comparability assessment could be done.
For glyphosate and AMPA, five out of six laboratories reported results. Results were comparable for both biomarkers in both control materials.
For the chlorpyrifos and pyrethroid biomarkers, three laboratories reported results for all seven biomarkers, and one for five biomarkers (no results for cis-DBCA and ClF3CA). In nine out of 14 cases, comparability of results could be demonstrated. In five cases, all for the same control material, the relative uncertainty of the mean was too high for a quantitative assessment of comparability.
Recommendations were made to further improve comparability of results in the next round.