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Information leaflets

What is the uncertainty factor?

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Published: Friday, 14 May 2021 23:00

Content

Distribution of GMO results showing approximately lognormal distribution

Appropriate expression of the measurement uncertainty (MU) is crucial, and there are situations when the traditional, symmetric, expanded uncertainty interval is not sufficient. This leaflet aims to explain the concept of the uncertainty factor and how it can be used to provide a convenient and realistic uncertainty interval in particular circumstances..

This leaflet was produced by the Eurachem Sampling Uncertainty Working Group and the Royal Society of Chemistry Analytical Methods Committee (AMC) Sampling Uncertainty Working Groups.

Availability

Translation

Please consult the Eurachem Sampling Uncertainty Working Group Chair, directly or by using the UfSWG contact form, if you would like to prepare a translation in your own language.

 

*Publication dates are dates of website publication. English version first published on this site on 2020-07-29.

Use of uncertainty information in compliance (2021)

Details
Published: Thursday, 29 April 2021 14:31

Content

Acceptance and rejection zones with a guard band used for high confidence of correct rejection ("Stringent Acceptance")This information leaflet is intended for laboratories perfoming chemical analyses. It has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group (see here for details) to introduce the use of decision rules and guard bands in interpreting results accompanied by measurement uncertainty information. The leaflet summarises the principles described in the Eurachem Guide "Use of uncertainty information in compliance assessment", which is available here.

This revised edition of this information leaflet is amended to reflect changes in the second edition of the compliance Guide.

Availability

 

* Publication dates are dates of publication on this website.

** First published 2021-09-01; amended 2021-12-09.

Translation

Translation into other languages is encouraged 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.

Note: The previous (2015) edition is available in English, Czech, Estonian, Finnish, Portuguese, Turkish and Ukrainian.

Previous editions

The previous edition of this leaflet can be found here.

The importance of method validation

Details
Published: Thursday, 25 February 2021 16:05

Content

Factors affecting PT strategy

Method validation is an important requirement in the practice of analytical science. ISO/IEC 17025, OECD guidelines on Good Manufacturing Practice and many similar codes of practice require some level of validation, whether by verification of the laboratory's implementation of published standard methods, or by comprehensive validation studies of new, in-house, procedures. Most analytical chemists are aware of its importance, but why it should be done, when, and exactly what needs to be done, is not always clear.

This leaflet, prepared by the Eurachem Method Validation working group, gives a brief introduction to the overall process of validation and the key performance characteristics to be studied, and provides pointers to more detailed guidance.

Availability

Translation

Please consult the Method Validation Working Group if you would like to prepare a translation in your own language.

 

*Publication dates are dates of website publication. English version first published on this site on 2021-02-25.

Investigating poor performance in proficiency testing

Details
Published: Tuesday, 07 January 2020 17:00

Content

Factors affecting PT strategyA laboratory will occasionally have a poor performance in a PT scheme. When this occurs, the laboratory should acknowledge it, carry out an investigation and document a review of possible causes, even if it decides not to take any specific action. This leaflet, prepared by the EURACHEM Proficiency Testing Working Group, gives advice for laboratories on how to best address such events.

This second edition is an editorial amendment to reference recent guidance on proficiency testing.

Availability

The second edition is currently available in the following languages. Links to translations of the first edition, available in 10 languages, are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared. 

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Previous editions

The first edition of this information leaflet can be found here, in our publication archive. Selected translations of the first edition are listed below for convenience pending translation of the second edition.

 

Notes

1. Dates show date of publication of the linked file on this website.

2. 2nd English edition first published 2022-07-30

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Proficiency testing schemes for sampling

Details
Published: Tuesday, 07 January 2020 17:00

Content

Factors affecting PT strategy

Proficiency Testing schemes for sampling play an important role in the improvement of sampling procedures and also in the development of participants from an educational point of view, especially if workshops with the participants are organised. PT schemes for sampling can also give an appreciation of the contribution of the sampling in relation to the overall quality of the measurement, including the associated contribution to the measurement uncertainty.

This leaflet, prepared by the EEE-PT Working Group, gives some hints on the application of ISO/IEC 17043 for PT providers organising PT schemes for sampling. If there is a comparison between participants and a mechanism for performance evaluation which meets the objective of the PT scheme for sampling, then ISO/IEC 17043 is applicable.

Availability

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

 

Notes

1. Dates show date of publication of the linked file on this website.

2. 2nd English edition first published 2020-07-29

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Use of surplus proficiency test items

Details
Published: Saturday, 09 November 2019 17:00

Content

Factors affecting PT strategyTest items are sometimes available from proficiency testing (PT) providers after the completion of a PT round. The EURACHEM Proficiency Testing Working Group has produced an information leaflet to advise laboratories on benefits and limitations of surplus PT items.

This second edition is an editorial amendment to reference recent guidance on PT.

Availability

The second edition is currently available in the following languages. Links to selected translations of the first edition are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared.

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Previous editions

The first edition of this information leaflet can be found here, in our publication archive, in nine languages. Selected translations of the first edition are listed below for convenience pending translation of the second edition.

 

Notes

1. Dates show date of publication of the linked file on this website.

2. 2nd English edition first published 2022-07-30

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ISO/IEC 17025:2017 - A New Accreditation Standard

Details
Published: Monday, 16 July 2018 18:00

Contents

ISO/IEC 17025 - 2005 and 2017 structures compared2017 saw the publication of a new version of ISO/IEC 17025 - General requirements for the competence of testing and calibration laboratories. Among other things, the new Standard adopted a substantially revised structure, including different management system options. The 2017 edition placed new emphasis on "risks and opportunities", included clearer reference to sampling activities, and added new requirements around conformity assessment and a new emphasis on metrological traceability.

This brief Information Leaflet, prepared by the Eurachem Education and training Working Group,  gives a quick overview of the main changes in the 2017 edition of the Standard.

Note: See 'Maintenance' below for further information on continued relevance of this Information Leaflet.

Availability

The leaflet is available in several different languages:

* File updated 2024-11-07 to correct link to Eurolab Cookbooks and update references

Translations

Translation into other languages is encouraged 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.

 

Maintenance of this information leaflet

As of 2023, the date of the most recent periodic reviewNote 1 of this Information Leaflet, ISO/IEC 17025:2017 is well established in accredited laboratories. The responsible Eurachem Working Group nonetheless consider that  information in the leaflet remains of current interest and have consequently confirmed the leaflet in its original form as current Eurachem guidance.

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Note 1. Eurachem policy on maintenance of Eurachem guidance can be found on the "Eurachem Policies and Procedures" page on this website.

Setting Target Measurement Uncertainty

Details
Published: Monday, 16 July 2018 16:25

Contents

orange tree trn 180Measurement results are only fit for purpose if the reported uncertainty is correct and has a magnitude small enough for the intended use. The target measurement uncertainty (target MU) is the maximum admissible uncertainty defined for a specific measurement goal. This information leaflet provides a short and accessible introduction to the idea of target measurement uncertainty.

For detailed information on setting a target measurement uncertainty, see the Eurachem/CITAC guide "Setting and Using Target Uncertainty in Chemical Measurement"

Availability

Translations

Translation into other languages is encouraged 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.

Proficiency testing - how much and how often?

Details
Published: Thursday, 12 January 2017 23:00

Content

Factors affecting PT strategyAn accredited laboratory needs to define in which PT schemes it should enrol  and how often it should participate. The EURACHEM Proficiency Testing Working Group has produced an information leaflet to help laboratories select the right balance of areas of work and participation frequency.

This second edition is an editorial revision to reference recent guidance on PT.

The second edition is currently available in English. Links to translations of the first edition, available in 12 languages, are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared.

Availability

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Previous editions

The first edition of this information leaflet can be found here, in our publication archive. Selected translations of the first edition are listed below for convenience pending translation of the second edition.

Notes

1. Dates show date of publication of the linked file on this website.

2. 2nd English edition first published 2022-07-30

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You talk, we understand – The way out of the tower of Babel

Details
Published: Friday, 04 December 2015 22:31

Contents

Babel 150This leaflet, prepared by the Eurachem Education and Training Working Group, explains the importance of having a common language when discussing measurements. It highlights some terms which are commonly confused or misunderstood, references the International Vocabulary of Metrology ("the VIM"), and introduces the Eurachem Guide on Terminology in Analytical Measurement.

This second edition updates the Information Leaflet to align with the second edition of the Eurachem Guide "Terminology in Analytical Measurement", published in 2023.

 

Availability

This second edition of the information leaflet is currently available in English. For translations of the previous edition, see 'previous editions', below.

1. Dates shown are dates of first publication on this website.

Translation

Translation into other languages is encouraged 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.

Previous editions

The first edition of this information leaflet can be found here, in our publication archive. Selected translations of the first edition are listed below for convenience pending translation of the second edition.

1. Amended April 2017