Measurement Uncertainty According to ISO 19036:2019

Ivana Ljevaković-Musladin

Abstract

ISO 19036 is an international standard that specifies and gives guidance for the estimation and expression of measurement uncertainty (MU) associated with quantitative results of microbial counts in foods. Standard describes top-down or global approach to MU, in which MU is calculated from experimental results with replication of the same analyses as part of the measurement process and expressed as a standard deviation of reproducibility of the final result. In a new revision from 2019 standard ISO 19036 considers three types of MU component: technical uncertainty, matrix uncertainty and distributional uncertainty. The aim of this study was to estimate all components of MU according to standard ISO 19036:2019. Technical uncertainty was estimated for quantitative enumeration tests for coagulasepositive staphylococci, Listeria monocytogenes, Escherichia coli, Enterobacteriaceae and aerobic mesophilic bacteria, while matrix uncertainty was estimated for ice cream, cheese, ready-to-eat vegetables, ready-to-eat food and cream cakes. Technical uncertainty was estimated from a reproducibility standard deviation of the final result of measurement process while the matrix uncertainty was estimated from within-sample variance by examination of multiple test portions from laboratory sample. Distributional uncertainty is estimated mathematically. The study showed that technical uncertainties of quantitative methods performed in our laboratory are the same magnitude and quite low. Matrix uncertainty was the largest contributor to combined uncertainty in composite food matrices. Our results are better than or in a close agreement with results from method validation interlaboratory studies and other published data.

Keywords

Measurement uncertainty; ISO 19036; Technical uncertainty; Matrix uncertainty; Distributional uncertainty

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IMEKO-TC10-2020-044.pdf

DOI

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IMEKO TC

TC10 - Measurement for Diagnostics, Optimization and Control

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