Practical and valid guidelines for realistic estimation of measurement uncertainty in multi-residue analysis of pesticides

To assist the understanding and adoption of measurement uncertainty principles in chemical tests, during the last decade, a number of specific guidelines have been published by EURACHEM/CITAC, EUROLAB, NORDTEST and others international bodies. All these guidelines agree that, in certain cases, the nature of the test method may preclude rigorous, metrologically and statistically valid, calculation of uncertainty of measurement, multi-residue analysis of pesticides being, without any doubt, one of these cases. In 2006, the Codex Alimentarius Commission established its guidelines on estimation of uncertainty of results for the determination of pesticide residues, which only include “empirical, practical or top-down” approaches based on whole-method performance investigations or scientific judgments from previous experience. The aim of this publication is to make a simple and comparative critical review of the most relevant international guidelines published on measurement uncertainty in both chemical analysis and pesticide residues analysis, extracting from them those proposals and practical conclusions that can be applied in a pesticide residue laboratory with full warranty and validity.