Published Guides

EURACHEM/CITAC leaflet: Setting Target Measurement Uncertainty, (July 16, 2018)

Ricardo Bettencourt da Silva, Alex Williams

EURACHEM/CITAC Guide: Guide to Quality in Analytical Chemistry – An Aid to Accreditation, 3rd Edition (2016)

Vicki BarwickThe aim of this guide is to provide laboratories with guidance on best practice for the analytical operations they carry out. The guidance covers both qualitative and quantitative analysis carried out on a routine or non-routine basis.

IUPAC/CITAC Guide: Classification, modeling and quantification of human errors in a chemical analytical laboratory (IUPAC Technical Report). Pure Appl. Chem. Vol. 88, No. 5, 477-515, 2016

Ilya Kuselman, Francesca PennecchiAbstract:The classification, modeling, and quantification of human errors in routine chemical analysis are described. Classifications include commission errors (mistakes and violations) and omission errors (lapses and slips) in different scenarios at different steps of the chemical analysis. A Swiss cheese model is used to characterize error interaction with a laboratory quality system. The quantification of human errors in chemical analysis, based on expert judgments, i.e. on the expert(s) knowledge and experience, is applied. A Monte Carlo simulation of the expert judgments was used to determine the distributions of the error quantification scores (scores of likelihood and severity, and scores of effectiveness of a laboratory quality system against the errors). Residual risk of human error after the error reduction by the laboratory quality system and consequences of this risk for quality and measurement uncertainty of chemical analytical results are discussed. Examples are provided using expert judgments on human errors in pH measurement of groundwater, multiresidue analysis of pesticides in fruits and vegetables, and elemental analysis of geological samples by inductively coupled plasma mass spectrometry.

EURACHEM/CITAC Guide: Setting and Using Target Uncertainty in Chemical Measurement, 1st Edition (2015)

Ricardo Bettencourt da Silva, Alex Williams

IUPAC/CITAC Guide: Investigating out-of specification test results of chemichal composition based on metrological concepts (IUPAC Technical Report). Pure Appl. Chem. Vol. 84, No. 9, 1939-1971, 2012,, 9 July 2012

Ilya Kuselman, Francesca Pennecchi, Cathy Burns, Aleš Fajgelj, Paolo de Zorzi 

EURACHEM/CITAC Guide CG4: Quantifying Uncertainty in Analytical Measurement, 3rd Edition (2012)

The 3rd edition is developed by the joint EURACHEM/CITAC WG, WG Chairman – Alex Williams

IUPAC/CITAC Guide: Selection and use of proficiency testing schemes for a limited number of participants – chemical analytical laboratories (IUPAC Technical Report). Pure Appl. Chem., Vol. 82, No 5, 2010, 1099-1135

Ilya Kuselman, Ales FajgeljAbstract: A metrological background for implementation of proficiency testing (PT) schemes for a limited number of participating laboratories (fewer than 30) is discussed. Such schemes should be based on the use of certified reference materials (CRMs) with traceable property values to serve as PT items whose composition is unknown to the participants. It is shown that achieving quality of PT results in the framework of the concept “tested once, accepted everywhere” requires both metrological comparability and compatibility of these results. The possibility of assessing collective/group performance of PT participants by comparison of the PT consensus value (mean or median of the PT results) with the certified value of the test items is analyzed. Tabulated criteria for this assessment are proposed. Practical examples are described for illustration of the issues discussed.

EURACHEM/EUROLAB/CITAC/Nordtest/UK RSC Analytical Methods Committee Guide: Measurement uncertainty arising from sampling.
WG Chairman – Michael H.Ramsey Þ

EURACHEM/CITAC Guide: Use of uncertainty information in compliance assessment. 
WG Chairman –  Alex Williams Þ

This guide is applicable to decisions on compliance with regulatory or manufacturing limits where a decision is made on the basis of a measurement result accompanied by information on the uncertainty associated with the result. It covers cases where the uncertainty does not depend on the value of the measurand, and cases where the uncertainty is proportional to the value of the measurand.

Traceability in Chemical Measurement. A guide to achieving comparable results in chemical measurement (2003)

This guide has been produced primarily by a joint EURACHEM/CITAC Working Group in collaboration with representatives from AOAC International and EA. Production of the guide was in part supported under the contract with the UK Department of Trade and Industry as part of the National Measurement System Valid Analytical Measurement (VAM) ProgrammeDownload Japanese

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

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. English language versions (edition 1.0 1998) are available from the Office of Reference Materials, LGC. Alternatively, you may download the guide from this website. Use Acrobat Reader.

Translated Guides

Guides translated to Portuguese

Letter from the Brazilian National Agency for Health“Guide to Quality in Analytical Chemistry” – “Guia para Qualidade em Química Analítica”“Selection, use and interpretation of proficiency testing (PT)” – “Seleção, Uso e Interpretação de Programas de Ensaios de Proficiência (EP)”“Accreditation for Microbiological Laboratories” – “Habilitação para Laboratórios de Microbiologia”

Guides translated to other languages

Quantifying Uncertainty in Analytical Measurement in Farsi (Persian Language) from Mohammad RahmaniQuantifying Uncertainty in Analytical Measurement in Spanish from Pedro Morillas

Information Leaflets

Metrological Traceability of Analytical Results –
in English,
in Spanish
Use of uncertainty information in compliance assessment –
in English,
in Turkish,
in Ukrainian

Publication Archive

Ilya Kuselman, Francesca Pennecchi, Cathy Burns, Ales Fajgelj, Paolo de Zorzi 
Investigating out-of-specification test results of chemical composition based on metrological concepts
Accred. Qual. Assur. (2010), 15, 283-288Abstract: A metrological background for investigating out-of-specification (OOS) test results of chemical composition is discussed. When an OOS test result is identified, it is important to determine its root causes and to avoid reoccurrence of such results. An investigation of the root causes based on metrological concepts would be beneficial. It includes (1) assessment of validation data of the measurement process, (2) evaluation of the measurement uncertainty contributions, and (3) assessment of metrological traceability chains critical for measurement parameters and environmental conditions influencing the test results. The questions, how can the validation data be applied for this investigation, and how can measurement uncertainty contributions and/or metrological traceability chains change a probability of OOS test results, are analyzed.
IUPAC/CITAC project 2008-030-1-500

Superseded Guides

Quantifying Uncertainty in Analytical Measurement, The Second Edition (2000)This guide has been produced primarily by a joint EURACHEM/CITAC Working Group in collaboration with representatives from AOAC International and EA. Production of the guide was in part supported under the contract with the UK Department of Trade and Industry as part of the National Measurement System Valid Analytical Measurement (VAM) Programme. The first version of this guide, which was published in 1995, has been very well received. It has been very widely used and two successful workshops on its utilisation have been held since its publication. Following from these workshops and the many helpful comments the working group has received on the contents of the first edition, many significant changes and improvements have been made in this second edition. The most important change deals with the use of method performance data and in particular the use of method validation data, from both collaborative validation studies and from in-house studies. The new sections dealing with the use of method performance data show that in many cases such data gives all, or nearly all information required to evaluate the uncertainty. The format of the guide is very similar to that of the first edition with chapters 1 and 2 dealing with the scope and the concept of uncertainty as before. Chapter 3, Analytical Measurement and Uncertainty, is completely new and covers the process of method validation and conduct of experimental studies to determine method performance and their relationship to uncertainty estimation. There is also a new section on traceability. The chapter on uncertainty estimation in the previous guide has been considerably expanded and split into four separate chapters, dealing with the four steps involved in estimating uncertainty. Step 1 deals with the specification of the measurand, Step 2 with identifying the uncertainty sources, Step 3, which has been considerably expanded to cover the use of existing method validation data, deals with quantifying the uncertainty and Step 4 covers the calculation of the combined uncertainty. The examples have been completely revised and new ones added. They are now all in a standard format, which follow the four steps described above. They all utilise the cause and effect diagram as an aid to identifying the sources of uncertainty and to ensuring that all the significant ones are included in the evaluation of the uncertainty. In addition a web site has been set up at URL which contains an indexed HTML version of the Guide. This site hosts a discussion forum on the application of the guide and has a section for the publication of additional examples.Printed hard copy will be available soon; please send enquiries either to the Eurachem Secretariat or the Office of Reference MaterialsLGC for UK copies.

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