'Bottom-up'- und 'Top-down'-Ansatze zur Ermittlung der Messunsicherheit am Beispiel der Pestizid-Bestimmung in Nahrungsmitteln

摘要

In chemical analysis the synthetic approach according to the Guide to the Expression of Uncertainty in Measurement (GUM), also called "bottom-up" approach, is not always sufficient for a complete evaluation of measurement uncertainty. Often a "top-down" approach is also necessary in which the variability of the final result to be expected under conditions usually occurring in practice is estimated as a measure of uncertainty using, e. g., validation results. A combination and a comparison of both kinds of approaches is presented using the determination of pesticide residues in food as an example.