How to deal with measurement uncertainty in routine mycotoxin determination

Analytical results form the basis for any decision taking process in official food control concerning mycotoxins (acceptance or rejection of goods). Therefore the correct interpretation of any analytical result is of key importance. Especially the fact that analytical results are associated with an uncertainty (probability dispersion around the result, within which the 'true' value most likely will fall) is of utmost significance, as the basis for any decision (e.g., rejection of goods) must be beyond reasonable doubt. This recently led to European Union legislation on mycotoxins in which uncertainty statements have to be taken into account when comparing analytical results with legislative limits. An uncertainty statement will have to consider the analyte concentration, the matrix to be analysed, the method used, etc. Therefore, there is no 'universal' or 'general' figure or method to determine it, thus uncertainty has to be estimated for each different analytical scenario. Several ways exist to estimate uncertainty and the most known monographs on this matter are probably the ISO Guide to the expression of uncertainty in measurement and the Eurachem Guide. One of the main aims in analytical laboratories implementing measurement uncertainty is that the estimation of measurement uncertainty must be logical and scientific. In addition to this, it must also be realistic and practical to establish for a testing laboratory, where possible. With a focus on this aim, several position papers, guidelines and procedures have been drafted to facilitate an estimate of uncertainty by practical means and the use of easy-to-generate or already existing data. Nevertheless the concepts of approaching uncertainty might differ. For example, some approaches involve the use of precision data derived from collaborative studies; others use mainly data from in-house experiments. The issue on how to deal with measurement uncertainty has been discussed at European Union expert level, which led to a report that aims to give guidelines on this matter with respect to official food control. The article below will give an overview of currently available procedures and discusses the practical aspects on how to implement measurement uncertainty into daily laboratory procedures and data interpretation.