CIPM MRA COMPARISON REPORTS

CCQM-K180

Polar analyte in high protein food matrix
U. Mülow-Stollin , J. Polzer , F. Tadjine , K. Heider , L. Johnston , E. Kakoulides , E. Skotidaki , E. Stathoudaki , V. Schoina , M. Bilsel ... , S. Gunduz , H. Yilmaz , I. Un , G. Bilsel , N. Chi-Shing , S. Hoi Yan Fiona , X. Li , S. Ling , Z. Qinghe , E.C.P. do Rego , F.G.M. Violante , R.V.P. Leal , T.M. Monteiro , W.S. Souza , J.L.N. Fernandes , L. Regalado Contreras , M. Maldonado Torres , E.B. Mercado Pedraza , M. Arce Osuna , G. Mcrae , S.W. Hyung , K. Choi , K. Shearman , A.R. Al-Askar , H. Klich , W. Bellazreg , S. Chaieb , O. Kesraoui , I. Ben Amor , E. Jridette , I. Ben Mbarek , K. Alimi , C. Hopley , V. Vekerya , C. Pui Sze , W. Juan , L. Ting , T. Tang Lin , A.S. Salinas Trujillo , J.H. Pulido , F.Y. Niño , A. Madrid Montoya , A. Mikheeva
Published on 20/03/2026 - © 2026 U. Mülow-Stollin et al
Citation U. Mülow-Stollin et al 2026 CIPM MRA Comparison reports 08013

Abstract

Metronidazole (and other nitroimidazoles) are banned worldwide in many countries (e.g., Canada, the European Union, the United States) for use in animals from which products for human consumption are derived, and effective food control is necessary to ensure consumer protection.

Evidence of successful participation in formal, relevant international comparisons is needed to document measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (DIs). At the CCQM Organic Analysis Working Group (OAWG) meetings in 2021 it was decided to organize a Track A comparison for polar analytes in a protein rich matrix in order to provide support of existing CMC claims (e.g. based on CCQM-K85 and CCQM-K141).

18 National Metrology Institutions registered in the Track A Key Comparison CCQM-K180, 17 thereof were able to import the test samples. Participants were requested to evaluate the mass fractions, expressed in μg/kg, of metronidazole in lyophilized porcine muscle material on a dry mass basis and should include standard and expanded uncertainties (95 % level of confidence).

Finally, all 17 National Metrology Institutions provided results, 15 of which were considered for the calculation of the key comparison reference value (KCRV). Applying the decision tree for KCRV selection to the final data set, it was decided to use the DerSimonian-Laird estimator (NIST consensus builder) for the KCRV calculation. Accordingly, the KCRV for metronidazole was calculated as 8.41 ± 0.08 μg/kg (with an associated dark uncertainty τ of 0.18 μg/kg).

Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).