Guides

Guides

Current Eurachem Guides

Quality Assurance for Research and Development and Non-routine Analysis (1998)

Contents

This guide, produced by a joint Eurachem/CITAC working party representing industrial, academic, and governmental interests, promotes and describes the concepts of quality assurance in the non-routine environment. The guide promotes a nested approach to quality assurance, dealing with it at a general organisational level, a technical level and a project specific level. It is intended to promote the use of QA as an effective tool for establishing and maintaining quality in R&D and non-routine operations. It does not seek to set criteria for accreditation of R&D although there is a section describing various methods for third party assessment of quality systems. The guidance may form the basis on which accreditation criteria can be set in the future. The guidance is intended to complement the existing CITAC guide (CG1) which describes QA in the routine environment. It is primarily directed towards analytical chemistry establishments but is, in principle, applicable to other sectors. An extensive bibliography is included.

Availability

The English language version (edition 1.0 1998) is available from the UK National Measurement System Chemical and Biological Metrology programme.

Download the guide from this website (new window) (pdf, 203 kB).

Translations

A German language version can be downloaded from the Eurachem/DE website documents page. (Opens new Browser window).

Translation into other languages is permitted for members of Eurachem. Other offers of translation should be directed to the Eurachem Secretariat for permission. The Eurachem policy on maintenance and development of Eurachem guidance, available on the Policies page, gives further information on translation.

Harmonised Guidelines for the Use of Recovery Information in Analytical Measurements (1998)

This guide was produced by IUPAC with contributions from Eurachem.

Contents

It is recognised that the use of recovery information to correct/adjust analytical results is a contentious one for analytical chemists. Different sectors of analytical chemistry have different practices. Formal legislative requirements with regard to the use of recovery factors also vary sector-to-sector. It is the aim of IUPAC, however, to prepare general Guidelines which may be seen to aid the preparation of the “best estimate of the true result” and to contribute to the comparability of the analytical results reported. IUPAC Interdivisional Working Party on Harmonisation of Quality Assurance Schemes for Analytical Laboratories has co-operated with the International Organisation for Standardisation (ISO), the International Association of Official Analytical Chemists (AOAC Int.) and Eurachem to produce this guide. On the basis of contributions presented at the Symposium on Harmonisation of Quality Assurance Systems for Analytical Laboratories dedicated to the “Use of Recovery Factors in Analytical Chemistry” (September 1996, Orlando, USA; sponsored by IUPAC, ISO and AOAC Int.) a final document was prepared for publication by M. Thompson, S. L. R. Ellison, A. Fajgelj, P. Willetts and R. Wood. The document was submitted for publication in Pure and Applied Chemistry.
This document attempts to give Guidelines that are intended to be general in their scope and give recommendations that reflect common practice best able to achieve the comparability of analytical results. However, specific sectors of analytical chemistry will need to develop these Guidelines for their own requirements and the recommendations are not, therefore, to be seen as binding for all areas of analytical chemistry.

Availability

An English language version is available from A. Fajgelj, Quality Assurance Supervisor, International Atomic Energy Agency, Agency's Laboratories Seibersdorf, 2444 Seibersdorf, Austria. Tel.: +43 1 2600 28233, Fax: + 43 1 2600 28222, E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.. Alternatively, you may download the guide from this website (pdf, 73 kB).

Translations

No other translations are currently available.

Measurement uncertainty arising from sampling (2nd edition, 2019)

Full title

UfS CoverMeasurement uncertainty arising from sampling: A guide to methods and approaches
Second edition (2019)

Contents

This Guide aims to describe various methods that can be used to estimate the uncertainties arising from the processes of sampling and the physical preparation of samples. It is intended primarily for specialists such as sampling planners and for analytical chemists who need to estimate the uncertainty associated with their measurement results.

The Guide deals with the case where the measurand is defined in term of the value of the analyte concentration in a sampling target, rather than in just the sample delivered to the laboratory. In this case, the sampling process affects the result and its uncertainty, and sampling is necessarily considered as part of the measurement process. This Guide takes a holistic view of the measurement process to include sampling and sample preparation as well as the analytical process.

The Guide begins by explaining the importance of the total uncertainty in a measurement for making reliable interpretation of measurements, and judging their fitness for purpose. It covers the whole measurement process, defining each of the component steps, and describing the effects and errors that cause uncertainty in the final result, with particular attention to sampling issues.

Two main approaches to the estimation of uncertainty from sampling are described. The empirical approach uses repeated sampling and analysis, under various conditions, to quantify the effects caused by factors such as the heterogeneity of the analyte in the sampling target and variations in the application of one or more sampling protocols, to quantify uncertainty (and usually some of its component parts). The modelling approach uses a predefined model that identifies each of the component parts of the uncertainty, making estimates of each component, and sums them in order to make an overall estimate.

For either approach, the Guide follows the principles of the ISO Guide to the Expression of Uncertainty in Measurement, interpreted for analytical measurement in the Eurachem guide "Quantifying Uncertainty in Analytical Measurement" which is available here.

This Second Edition includes a number of additions and changes. These include

  • the expression of uncertainty of measurement as an 'uncertainty factor' (FU) when the frequency distribution describing the sampling uncertainty is log-normal rather than normal, and guidance on the use of an uncertainty factor in an uncertainty budget.
  • the use of an unbalanced design to estimate uncertainty more cost-effectively than can be achieved using the balanced ‘duplicate method’ design;
  • updates to definitions and references to reflect current international documents and literature, including applications of these methods to on-site and in situ measurements, made at both the macro and the micro scale.

Availability

From this website:

* Also available from the ISS website.

Additional translations:

Note: In parallel with this Eurachem Guide on sampling uncertainty, Nordtest developed a shorter handbook on sampling, which is available from the Nordtest website.

Editorial corrections

A small number of editorial corrections have been identified since the edition above was approved. These are listed in the sheet of Errata below.

Note: The Spanish edition (UfS:2019.P2-ES) published 2021-05-25 includes the corrections listed in the above correction list, up to errata version 1.2.

Citation

This Guide should be cited* as:

M H Ramsey, S L R Ellison and P Rostron (eds.) Eurachem/EUROLAB/ CITAC/Nordtest/AMC Guide: Measurement uncertainty arising from sampling: a guide to methods and approaches. Second Edition, Eurachem (2019). ISBN (978-0-948926-35-8). Available from http://www.eurachem.org

*Subject to journal requirements.

Translations

Translation into other languages is permitted for members of Eurachem. Other offers of translation should be directed to the Eurachem Secretariat for permission. The Eurachem policy on maintenance and development of Eurachem guidance, available on the Policies page, gives further information on translation.

Translations of the First edition can be found in the publication archive, here.

Quantifying Uncertainty in Analytical Measurement, 3rd Edition (2012)

Contents

This guide has been produced by a joint EURACHEM/CITAC Measurement Uncertainty Working Group.

Cause and Effect diagramThe first edition of the EURACHEM Guide for “Quantifying Uncertainty in Analytical Measurement” was published in 1995 based on the ISO "Guide to the Expression of Uncertainty in Measurement". The second edition was prepared in collaboration with CITAC in 2000 in the light of practical experience of uncertainty estimation in chemistry laboratories and the even greater awareness of the need to introduce formal quality assurance procedures by laboratories. The second edition stressed that the procedures introduced by a laboratory to estimate its measurement uncertainty should be integrated with existing quality assurance measures, since these measures frequently provide much of the information required to evaluate the measurement uncertainty.

This third edition retains the features of the second edition and adds information based on developments in uncertainty estimation and use since 2000. The additional material provides:

  • Improved guidance on the expression of uncertainty near zero; Monte Carlo uncertainty evaluation
  • New guidance on the use of Monte Carlo methods for uncertainty evaluation;
  • Improved guidance on the use of proficiency testing data:
  • Improved guidance on the assessment of compliance of results with measurement uncertainty.

The guide therefore provides explicitly for the use of validation and related data in the construction of uncertainty estimates in full compliance with the formal ISO Guide principles set out in the ISO Guide to the Expression of Uncertainty in measurement. The approach is also consistent with the requirements of ISO/IEC 17025:2005.

Availability

You may download the guide from this website at no cost (pdf, 1.908 MB).

NB: See also "Comments and errata" below.

Citation

This guidance should be cited* as
"S L R Ellison and A Williams (Eds). Eurachem/CITAC guide: Quantifying Uncertainty in Analytical Measurement, Third edition, (2012) ISBN 978-0-948926-30-3. Available from www.eurachem.org."

*Subject to journal requirements.

Translations

Available translations

The current (third) edition of this guide is currently available for download in English Farsi*, Spanish* and Japanese*.

Note 1. Translation first published 2018-08-06: editorial amendment published 2022-07-31

In addition:

See also "Previous editions", below, for earlier translations.

Translating this guide

Eurachem members are entitled to prepare translations of Eurachem guidance in their own language. Other organisations or individuals must request permission from the Eurachem Executive to undertake or publish translations. The Eurachem policy on maintenance and development of Eurachem guidance, available on the Policies page, gives further information on translation.

Comments and errata

Since publication of the third edition of the Guide in 2012, a number of minor typographical issues have been identified. Although not sufficient to justify revision and re-issue of the complete Guide and translations, some affect the detailed results of calculations in examples, making it hard to check results exactly. The Measurement Uncertainty and Traceability WG have accordingly prepared a list of comments and corrections for reader information. These are likely to be implemented in future editions.

Previous editions

The previous editions in English are available from this website:

Some translations of earlier editions are also available from respective national members or elsewhere. The 2nd edition has been translated into Italian, Portuguese, Russian and Swedish. The Italian translation of the 2nd edition can be downloaded from the Eurachem Guide page on the INRIM website. For details about the translation of the 2nd edition of the Guide into Russian please contact This email address is being protected from spambots. You need JavaScript enabled to view it. from the D. I. Mendeleyev Institute for Metrology. The 1st edition (1995) has been translated into Czech, Lithuanian, Russian and Spanish. For details about older translations please contact the Eurachem representative in the respective country or the Eurachem Secretariat

Acknowledgements

Production of the English edition of the guide was supported by the UK National Measurement System.

The Spanish translation of the 3rd edition was provided by P Morillas (Spain) and the Farsi translation by Mohammad Rahmani (Iran).

The Japanese translation is also commercially available from the publisher Maruzen Publishing: see https://www.maruzen-publishing.co.jp/ or  Amazon Japan.

Contact point

Any comment or query about the content of this guide should be directed to the Working Group Secretary.

 

Figures

1. Cause and Effect diagram: Uncertainty sources in leachable cadmium measurement

2. A histogram of 500 Monte Carlo simulations. See Appendix E.3 in the Guide for details