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Sampling and analysis of Measurement uncertainty

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Guest user Created:   Jan 13, 2020 Last commented:   Jan 13, 2020

Sampling and analysis of Measurement uncertainty

I attended a Workshop last year - Uncertainty from sampling and analysis for accredited laboratories. I presented a PowerPoint about an approach of Uncertainty in sampling for microbiology analysis. In XYZ, our Accreditation Body still wants the presentation of sampling and analysis uncertainty or the measurement uncertainty in the report. The problem is that we do not have a standard or a guide to calculate it as we saw on the presentation of the ILAC. Do you know any document that has been published since then?
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Tracey Evans Jan 13, 2020

The 2002 version of the ILAC document,  ILAC G17 (Introducing the Concept of Uncertainty of Measurement in Testing in Association with the Application of the Standard ISO/IEC 17025) is still under revision. Accreditation bodies should acknowledge that even ILAC states that there is currently not enough guidance and a lack of rules for implementing Uncertainty in sampling, i.e. reporting separately as sMU (see https://www.eurachem.org/images/stories/workshops/2019_11_MU/pdf/P1-09_ILAC_UfS_guidance_Oehlenschlaeger.pdf).   

 
I would say that until the ILAC decision is communicated after the March 2020 Beijing meeting, there is justification to merely interpret and comply with the ISO 17025:2017 requirements for measurement uncertainty evaluation (as discussed in the ILAC presentation). Besides the latest Eurachem guideline Measurement uncertainty arising from sampling, 2nd edition (2019), available at https://www.eurachem.org/index.php/publications/guides/musamp; the primary normative ISO standards are the ISO 98 series, including

  • ISO/IEC GUIDE 98-1:2009 [JCGM/WG1/104] Uncertainty of measurement - Part 1: Introduction to the expression of uncertainty in measurement;
  • ISO/IEC Guide 98-3:2008(en) Uncertainty of measurement - Part 3: Guide to the expression of uncertainty in measurement (GUM:1995);
  • ISO/IEC Guide 98-4:2012 Uncertainty Of Measurement - Part 4: Role Of Measurement Uncertainty In Conformity Assessment

Then for Microbiology, there is the recently revised ISO 19036:2019 Microbiology of the food chain - Estimation of measurement uncertainty for quantitative determinations.  Trust this is of some assistance.

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