Overview
EN ISO 19036:2019 - titled "Microbiology of the food chain - Estimation of measurement uncertainty for quantitative determinations" - is a CEN-adopted international standard that specifies requirements and gives guidance for estimating and expressing measurement uncertainty (MU) in quantitative microbiological results. It applies to analyses of products for human or animal consumption, environmental samples from food production/handling, and samples at primary production stages. Typical methods covered include colony‑count techniques, but the standard is also generally applicable to most probable number (MPN), instrumental methods (impediometry, ATP, flow cytometry), and molecular methods such as qPCR. Note: the MU estimated by this standard does not include systematic effects (bias).
Key Topics
- Scope & applicability: quantitative microbiology across the food chain - food, feed, environment, primary production.
- Identification of uncertainty sources:
- Technical uncertainty (laboratory method variability; intralaboratory and interlaboratory components).
- Matrix uncertainty (microbial dispersion within the sample matrix).
- Distributional uncertainties (e.g., Poisson uncertainty for colony counts).
- Confirmation uncertainty (uncertainty from confirmatory tests following presumptive counts).
- MPN uncertainty for probabilistic enumeration methods.
- Experimental design: guidance for intralaboratory reproducibility experiments aligned with ISO 16140-3 practices.
- Estimation methods:
- Derivation of reproducibility standard deviations from intra- and interlaboratory data.
- Combining technical, matrix, and distributional components to calculate combined standard uncertainty and expanded uncertainty.
- Reporting requirements: how to express MU in test reports, including treatment of results below limits of quantification.
- Supporting materials: worked examples and informative annexes on calculations, matrix effects, and correction of unwanted components.
Applications
EN ISO 19036:2019 is practical for:
- Food and feed testing laboratories establishing and reporting uncertainty on quantitative microbiology results.
- Quality assurance and laboratory managers implementing MU estimation into SOPs and accreditation evidence.
- Regulatory bodies and auditors assessing the confidence and comparability of reported microbial counts.
- Method developers and researchers evaluating precision and limits of quantitative microbiological methods, including colony counts, MPN, ATP/impediometry, flow cytometry, and qPCR.
Practical benefits include improved interpretation of microbial counts, better risk-based decision making, harmonized reporting, and strengthened conformity with accreditation requirements.
Related Standards
- ISO/IEC Guide 98-3 (GUM) - foundational principles for measurement uncertainty.
- ISO 16140-3 - experimental design for verification of quantitative methods (referenced for intralaboratory reproducibility).
- Historical: ISO/TS 19036:2006 / Amd.1:2009 (previous technical specification replaced by this edition).
Keywords: EN ISO 19036:2019, measurement uncertainty, microbiology of the food chain, colony count, MPN, qPCR, ATP, matrix uncertainty, Poisson uncertainty, intralaboratory reproducibility.
