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Information leaflets

Proficiency testing schemes for sampling

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

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.help laboratories select the right balance of areas of work and participation frequency.

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

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 2024-05-11 to correct link to Eurolab Cookbooks

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

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?

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

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

Selecting the right proficiency testing scheme for my laboratory

Content

EURACHEM through its Proficiency Testing Working Group has produced an information leaflet to help laboratories select the most appropriate proficiency testing schemes. Several PT schemes are often available for the same area of testing, so this leaflet focuses on key questions that can help laboratories choose those PT schemes that are best suited for their needs.

This second edition updates the leaflet to reference current guidance on PT.

Availability

The second edition is currently available in the following languages. Links to translations of the first edition, available in 14 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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Using repeated measurements to improve the standard uncertainty

Content

Analysts often take multiple observations, and sometimes average the result of several observations to reduce the uncertainty associated with random variation. However, it is often unclear how the standard uncertainty associated with averaged results should be calculated from an observed standard deviation. Sometimes one should divide by the square root of the number of observations; sometimes the standard deviation is used unchanged, and sometimes some alternative formula is appropriate. 

This information leaflet has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group (see here for details) to give further explanation of when the classical 'root n' formula can, and can not, be used. The leaflet amplifies principles described in the Eurachem Guide "Quantifying uncertainty in analytical measurement", which is available here.

 

Availability

*2015 edition

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.

Amendment history

This leaflet was amended to improve clarity in April 2016. The previous English version, as issued in 2015, is available for comparison.

Treatment of an observed bias

Content

bias img 240x194Bias is routinely determined during the validation of analytical methods. Usually, the observed bias is not exactly zero. It is then important to decide whether the observed bias can reasonably be treated as unimportant, or whether some further action needs to be taken. This can be particularly difficult to decide when applying the principles of the 'Guide to the Expression of Uncertainty in measurement', which assumes that a correction has been applied for any important bias. 

This information leaflet has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group (see here for details). The leaflet discusses whether or not an observed significant bias should be corrected and the impact this may have on the measurement uncertainty (MU). The leaflet does not describe how to apply a correction or how to increase the uncertainty to take account of an uncorrected bias, though it does provide relevant literature sources.

 

Availability

 * 2nd printing; editorial amendment only

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.

Publication date

This leaflet was first published in English on 2017-05-27.

* The English copy on this page is a minor (editorial) amendment, published 2022-10-21; the recommendations are unchanged.

Traceability of Analytical Results

Content

Octopus 1 195x182This information leaflet is intended for laboratories perfoming chemical analyses. It has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group to summarise the principles of metrological traceability in routine testing. It follows the general principles of the Eurachem Guide "Traceability in Chemical Measurement", which is available here.

The leaflet was first issued in 2005. A revised version, updated for relevance to ISO/IEC 17025:2017, was published in 2019.

Availability

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

Earlier editions of this leaflet, including translations in Spanish and Portuguese, can be found in the publication archive.