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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.11, #8-9)
Proficiency testing workshop – a key triennial event
by Brian Brookman; Nineta Majcen (pp. 371-372).
Proficiency testing workshop – a key triennial event
by Brian Brookman; Nineta Majcen (pp. 371-372).
Fitness for purpose – the integrating theme of the revised Harmonised Protocol for Proficiency Testing in Analytical Chemistry Laboratories by Michael Thompson; Stephen L. R. Ellison (pp. 373-378).
An overview is presented of the changes in, and rationale of, the 2006 IUPAC Harmonised Protocol for Proficiency Testing in Analytical Chemistry Laboratories. Much experience has accumulated and research has been undertaken since the publication of the first edition of the Harmonised Protocol in 1995. Happily, this experience demonstrated no need for the re-examination of the principles underlying the protocol. However, considerable advances were evident in the way in which the protocol could be put into practice. The most prominent of these advances stems from the increasing awareness of uncertainty as a metrological concept and the corresponding clarification of the idea of fitness for purpose. Fitness for purpose provides a rational basis for converting participants’ results into scores, a basis that provides scores that are fully comparable over many different types of analysis.
Keywords: Proficiency testing; Fitness for purpose; Harmonised protocol
Fitness for purpose – the integrating theme of the revised Harmonised Protocol for Proficiency Testing in Analytical Chemistry Laboratories by Michael Thompson; Stephen L. R. Ellison (pp. 373-378).
An overview is presented of the changes in, and rationale of, the 2006 IUPAC Harmonised Protocol for Proficiency Testing in Analytical Chemistry Laboratories. Much experience has accumulated and research has been undertaken since the publication of the first edition of the Harmonised Protocol in 1995. Happily, this experience demonstrated no need for the re-examination of the principles underlying the protocol. However, considerable advances were evident in the way in which the protocol could be put into practice. The most prominent of these advances stems from the increasing awareness of uncertainty as a metrological concept and the corresponding clarification of the idea of fitness for purpose. Fitness for purpose provides a rational basis for converting participants’ results into scores, a basis that provides scores that are fully comparable over many different types of analysis.
Keywords: Proficiency testing; Fitness for purpose; Harmonised protocol
Surveys on the accreditation of providers of proficiency testing and external quality assessment schemes by Anita Schmidt; Ulf Örnemark; Manfred Golze; Gitte Marie Henriksen (pp. 379-384).
Two surveys among providers of proficiency testing (PT) and external quality assessment (EQA) schemes were carried out during 2004 and 2005. The main objectives were to explore the current status of accreditation/certification and collect the providers’ views. Information based on the response from 160 providers in 32 countries reveals a strong tendency towards accreditation of PT/EQA. It is shown that this type of accreditation is based on several combinations of normative documents, hence illustrating a lack of harmonisation of national accreditation bodies. The surveys also show that schemes are operated under considerably different conditions and that providers’ competence may or may not be underpinned by other certification and/or accreditation. This paper elaborates on a number of issues related to PT/EQA accreditation, including customers’ views, normative documents, providers’ experience from the accreditation process, views expressed by international organisations, and effects of accreditation on participation fees, quality and availability.
Keywords: Interlaboratory comparison; Proficiency testing; External quality assessment; Accreditation; Certification
Surveys on the accreditation of providers of proficiency testing and external quality assessment schemes by Anita Schmidt; Ulf Örnemark; Manfred Golze; Gitte Marie Henriksen (pp. 379-384).
Two surveys among providers of proficiency testing (PT) and external quality assessment (EQA) schemes were carried out during 2004 and 2005. The main objectives were to explore the current status of accreditation/certification and collect the providers’ views. Information based on the response from 160 providers in 32 countries reveals a strong tendency towards accreditation of PT/EQA. It is shown that this type of accreditation is based on several combinations of normative documents, hence illustrating a lack of harmonisation of national accreditation bodies. The surveys also show that schemes are operated under considerably different conditions and that providers’ competence may or may not be underpinned by other certification and/or accreditation. This paper elaborates on a number of issues related to PT/EQA accreditation, including customers’ views, normative documents, providers’ experience from the accreditation process, views expressed by international organisations, and effects of accreditation on participation fees, quality and availability.
Keywords: Interlaboratory comparison; Proficiency testing; External quality assessment; Accreditation; Certification
Experiences from the assessment of proficiency testing providers by Katherine Monnery (pp. 385-387).
Following a pilot project in 2001–2002, UKAS accredited nine PT providers. During the course of the pilot and at subsequent surveillance visits, UKAS has gained experience in assessing organisations against the criteria detailed within ISO/IEC Guide 43-1:1997 and ILAC G13:2000. This article explores some of the key aspects that arose during the pilot and how UKAS has accommodated the addition of the accreditation of PT providers in to its range of services.
Keywords: Accreditation; United Kingdom Accreditation Service (UKAS); Proficiency testing; ISO Guide 43; ILAC G13
Experiences from the assessment of proficiency testing providers by Katherine Monnery (pp. 385-387).
Following a pilot project in 2001–2002, UKAS accredited nine PT providers. During the course of the pilot and at subsequent surveillance visits, UKAS has gained experience in assessing organisations against the criteria detailed within ISO/IEC Guide 43-1:1997 and ILAC G13:2000. This article explores some of the key aspects that arose during the pilot and how UKAS has accommodated the addition of the accreditation of PT providers in to its range of services.
Keywords: Accreditation; United Kingdom Accreditation Service (UKAS); Proficiency testing; ISO Guide 43; ILAC G13
Accreditation of PT providers – is it worth the money? by Anthony J. Russell; Ulf Örnemark; Lena Hård; Gunnar Nordin (pp. 388-390).
This topic is being presented from two perspectives, namely the views of an accreditation body and those of an accredited provider of external quality assessment schemes. The first perspective, from an accreditation body, is based on the experience of Australia's national laboratory accreditation body (NATA), which has accredited fourteen proficiency testing (PT) providers and is currently processing an application from another. The second perspective is based on the experience of EQUALIS, the national quality assurance organisation for laboratory medicine in Sweden, which was granted accreditation in 2002.
Keywords: Proficiency testing; External quality assessment; Accreditation; Value for money
Accreditation of PT providers – is it worth the money? by Anthony J. Russell; Ulf Örnemark; Lena Hård; Gunnar Nordin (pp. 388-390).
This topic is being presented from two perspectives, namely the views of an accreditation body and those of an accredited provider of external quality assessment schemes. The first perspective, from an accreditation body, is based on the experience of Australia's national laboratory accreditation body (NATA), which has accredited fourteen proficiency testing (PT) providers and is currently processing an application from another. The second perspective is based on the experience of EQUALIS, the national quality assurance organisation for laboratory medicine in Sweden, which was granted accreditation in 2002.
Keywords: Proficiency testing; External quality assessment; Accreditation; Value for money
Comparability of PT schemes – what did we learn from COEPT? by Nick Boley; Adriaan M. H. van der Veen; Piotr Robouch; Manfred Golze; Johannes van de Kreeke; Ulf Örnemark; Barry Tylee (pp. 391-399).
The use of proficiency testing schemes (PTS) by laboratories as an integral part of their quality system has been increasing in recent years. Accreditation bodies, regulators and the laboratories’ customers are increasingly using results from PTS in their relationship with laboratories. There are many PTS available in Europe in analytical chemistry; EPTIS indicates over 400.The comparability of these PTS is now a real issue, as many organisers of PTS move into new markets. The COEPT project has systematically demonstrated (in four technical sectors – water, soil, food and occupational hygiene), that there are many similarities between PTS in each sector. For example, nearly all use the z-score as a performance index. One significant difference between many PTS is the value used for the term s in the z-score equation, and this gives a range of evaluations for the same data point. Despite this, the agreement between PTS in the same sector for the evaluation of data is approximately 85%. COEPT has given us a basis for establishing the comparability of PTS and showing us where further harmonisation could occur.
Keywords: Proficiency testing; Comparability; Harmonisation
Comparability of PT schemes – what did we learn from COEPT? by Nick Boley; Adriaan M. H. van der Veen; Piotr Robouch; Manfred Golze; Johannes van de Kreeke; Ulf Örnemark; Barry Tylee (pp. 391-399).
The use of proficiency testing schemes (PTS) by laboratories as an integral part of their quality system has been increasing in recent years. Accreditation bodies, regulators and the laboratories’ customers are increasingly using results from PTS in their relationship with laboratories. There are many PTS available in Europe in analytical chemistry; EPTIS indicates over 400.The comparability of these PTS is now a real issue, as many organisers of PTS move into new markets. The COEPT project has systematically demonstrated (in four technical sectors – water, soil, food and occupational hygiene), that there are many similarities between PTS in each sector. For example, nearly all use the z-score as a performance index. One significant difference between many PTS is the value used for the term s in the z-score equation, and this gives a range of evaluations for the same data point. Despite this, the agreement between PTS in the same sector for the evaluation of data is approximately 85%. COEPT has given us a basis for establishing the comparability of PTS and showing us where further harmonisation could occur.
Keywords: Proficiency testing; Comparability; Harmonisation
Use of participant EQA results to assess sample homogeneity and stability for qualitative analytes by Daniel Tholen; Roderick Chappel; Barbara Francis (pp. 400-407).
International requirements for PT and EQA state that providers must demonstrate that samples are homogeneous and stable. However, testing for homogeneity and stability can be expensive, use samples that could otherwise serve as quality-control materials, and can also fail to detect significant inhomogeneity and instability. In some situations it may be preferable to use the results from participants to identify problems with sample lots, if historic results follow predictable distributions and a statistical decision rule can be produced. An unusually high proportion of incorrect results may indicate that samples were inhomogeneous or unstable. Conditions under which this can be demonstrated are discussed, and the efficacy of the proposal is demonstrated with two examples. This procedure is especially effective when there are a large number of participants and/or a historic small proportion of incorrect results. Providers who adopt this proposal will need to retain samples for testing and assume the risk of distributing bad samples.
Keywords: Proficiency testing; Homogeneity; Serology; Food testing
Use of participant EQA results to assess sample homogeneity and stability for qualitative analytes by Daniel Tholen; Roderick Chappel; Barbara Francis (pp. 400-407).
International requirements for PT and EQA state that providers must demonstrate that samples are homogeneous and stable. However, testing for homogeneity and stability can be expensive, use samples that could otherwise serve as quality-control materials, and can also fail to detect significant inhomogeneity and instability. In some situations it may be preferable to use the results from participants to identify problems with sample lots, if historic results follow predictable distributions and a statistical decision rule can be produced. An unusually high proportion of incorrect results may indicate that samples were inhomogeneous or unstable. Conditions under which this can be demonstrated are discussed, and the efficacy of the proposal is demonstrated with two examples. This procedure is especially effective when there are a large number of participants and/or a historic small proportion of incorrect results. Providers who adopt this proposal will need to retain samples for testing and assume the risk of distributing bad samples.
Keywords: Proficiency testing; Homogeneity; Serology; Food testing
Practical uses of proficiency testing as valuable tools for validation and performance assessment in environmental analysis by Rose Detaille; Philippe Maetz (pp. 408-413).
Besides their role as an external quality control tool, PT results or samples could be used as an alternative to fulfil some of the quality assurance requirements such as analytical precision, uncertainty assessment, and internal quality control. This additional use of proficiency testing could help laboratories to reduce the financial impact of their quality assurance process. The purpose of this paper is to highlight some practical uses of PT results or samples in the environmental analytical field, which have been implemented at ISSeP (Institut Scientifique de Service Public), either for method validation or for internal quality control.
Keywords: Proficiency testing; Analytical validation; Quality control
Practical uses of proficiency testing as valuable tools for validation and performance assessment in environmental analysis by Rose Detaille; Philippe Maetz (pp. 408-413).
Besides their role as an external quality control tool, PT results or samples could be used as an alternative to fulfil some of the quality assurance requirements such as analytical precision, uncertainty assessment, and internal quality control. This additional use of proficiency testing could help laboratories to reduce the financial impact of their quality assurance process. The purpose of this paper is to highlight some practical uses of PT results or samples in the environmental analytical field, which have been implemented at ISSeP (Institut Scientifique de Service Public), either for method validation or for internal quality control.
Keywords: Proficiency testing; Analytical validation; Quality control
Proficiency testing of chloride content in different types of Portland cement by Franc Švegl; Jerneja Šuput Strupi; Irena Grabec Švegl (pp. 414-421).
The accurate determination of chloride content in cement is a prerequisite for the production of high-quality concrete due to the damaging influence of free chloride ions on durability and safety of concrete constructions. The results for total chloride content in four different types of Portland cement provided by testing laboratories participating in an inter-laboratory comparison are presented. The data sets were evaluated by using different statistical methods. The laboratories exceeding critical values were signaled and sources of error were investigated. The precision parameters of the method were determined and the variance of the entire data set was apportioned among the sources of variation. The systematic differences between participating laboratories and heterogeneity of the cement samples were identified as major sources of variability of results. The ANOVA determined the intermediate precision parameters, which showed a low value for random errors resulting in good repeatability and high impact of sample and inter-laboratory difference on reproducibility of the method.
Keywords: Cement; Inter-laboratory comparison; Conformity; Free chlorides; ANOVA
Proficiency testing of chloride content in different types of Portland cement by Franc Švegl; Jerneja Šuput Strupi; Irena Grabec Švegl (pp. 414-421).
The accurate determination of chloride content in cement is a prerequisite for the production of high-quality concrete due to the damaging influence of free chloride ions on durability and safety of concrete constructions. The results for total chloride content in four different types of Portland cement provided by testing laboratories participating in an inter-laboratory comparison are presented. The data sets were evaluated by using different statistical methods. The laboratories exceeding critical values were signaled and sources of error were investigated. The precision parameters of the method were determined and the variance of the entire data set was apportioned among the sources of variation. The systematic differences between participating laboratories and heterogeneity of the cement samples were identified as major sources of variability of results. The ANOVA determined the intermediate precision parameters, which showed a low value for random errors resulting in good repeatability and high impact of sample and inter-laboratory difference on reproducibility of the method.
Keywords: Cement; Inter-laboratory comparison; Conformity; Free chlorides; ANOVA
Macrozoobenthos interlaboratory comparison on taxonomical identification and counting of marine invertebrates in artificial sediment samples including testing various statistical methods of data evaluation by Petra Schilling; Martin Powilleit; Steffen Uhlig (pp. 422-429).
A macrozoobenthos interlaboratory comparison was carried out by 16 laboratories to check the taxonomical expertise and the precision of sorting and counting. Participating laboratories had to determine and count in an artificial sediment sample 22 selected macrozoobenthos species taken from the western Baltic Sea. Two methods for the analysis of data were applied: assessment of qualitative and quantitative successful hits and the maximum-likelihood method.The results of counting were mostly precise (one lab without mistake). Four laboratories had a rate of false determination of 10%, eight laboratories between 10 and 20% and four laboratories of more than 20%.The species Arctica islandica, Retusa obtusa, Fabricia stellaris, Polydora quadrilobata, Pholoe assimilis, Microdeutopus gryllotalpa, and Corophium crassicorne caused some problems at the species determination step.The comparison of the different methods of statistical data analysis shows that the maximum-likelihood method is more sensitive than the method of successful hits.
Keywords: Macrozoobenthos; Taxonomical determination; Counting; Interlaboratory comparison; Marine monitoring
Macrozoobenthos interlaboratory comparison on taxonomical identification and counting of marine invertebrates in artificial sediment samples including testing various statistical methods of data evaluation by Petra Schilling; Martin Powilleit; Steffen Uhlig (pp. 422-429).
A macrozoobenthos interlaboratory comparison was carried out by 16 laboratories to check the taxonomical expertise and the precision of sorting and counting. Participating laboratories had to determine and count in an artificial sediment sample 22 selected macrozoobenthos species taken from the western Baltic Sea. Two methods for the analysis of data were applied: assessment of qualitative and quantitative successful hits and the maximum-likelihood method.The results of counting were mostly precise (one lab without mistake). Four laboratories had a rate of false determination of 10%, eight laboratories between 10 and 20% and four laboratories of more than 20%.The species Arctica islandica, Retusa obtusa, Fabricia stellaris, Polydora quadrilobata, Pholoe assimilis, Microdeutopus gryllotalpa, and Corophium crassicorne caused some problems at the species determination step.The comparison of the different methods of statistical data analysis shows that the maximum-likelihood method is more sensitive than the method of successful hits.
Keywords: Macrozoobenthos; Taxonomical determination; Counting; Interlaboratory comparison; Marine monitoring
Virtual microscopy: Revolutionary means for EQAS in a near future
by Jean-Claude Libeer (pp. 430-434).
Virtual microscopy: Revolutionary means for EQAS in a near future
by Jean-Claude Libeer (pp. 430-434).
Occupational and environmental laboratory medicine: A network of EQAS organisers by Andrew Taylor; Jurgen Angerer; Josiane Arnaud; Françoise Claeys; Robert L. Jones; Olav Mazarrasa; Eric Mairiaux; Antonio Menditto; Patrick J. Parsons; Marina Patriarca; Alain Pineau; Sinikka Valkonen; Jean-Philippe Weber; Cas Weykamp (pp. 435-439).
Most people in any community come into contact with chemicals that are potentially harmful to their health. Some elements are essential to health and inadequate amounts in food may also lead to ill health. Measurement of chemicals in blood, urine or other specimens is a fundamental feature of studies undertaken in the field of Occupational and Environmental Laboratory Medicine (OELM). Results are used to assess the risk for either overexposure or deficiency of essential nutrients. External Quality Assessment Schemes (EQAS) aid laboratories to achieve accurate and consistent data and 11 organisers of EQAS in Europe and North America are working to improve the effectiveness of their activities.The aims of the Network of EQAS Organisers in OELM are to stimulate improvements in analytical results, establish equivalence of assessment among Schemes, collaborate to enhance the practice of EQA including whenever possible to warrant traceability of EQAS to primary standards.
Keywords: Occupational and environmental laboratory medicine; Equivalence of assessment; Traceability; Uncertainty
Occupational and environmental laboratory medicine: A network of EQAS organisers by Andrew Taylor; Jurgen Angerer; Josiane Arnaud; Françoise Claeys; Robert L. Jones; Olav Mazarrasa; Eric Mairiaux; Antonio Menditto; Patrick J. Parsons; Marina Patriarca; Alain Pineau; Sinikka Valkonen; Jean-Philippe Weber; Cas Weykamp (pp. 435-439).
Most people in any community come into contact with chemicals that are potentially harmful to their health. Some elements are essential to health and inadequate amounts in food may also lead to ill health. Measurement of chemicals in blood, urine or other specimens is a fundamental feature of studies undertaken in the field of Occupational and Environmental Laboratory Medicine (OELM). Results are used to assess the risk for either overexposure or deficiency of essential nutrients. External Quality Assessment Schemes (EQAS) aid laboratories to achieve accurate and consistent data and 11 organisers of EQAS in Europe and North America are working to improve the effectiveness of their activities.The aims of the Network of EQAS Organisers in OELM are to stimulate improvements in analytical results, establish equivalence of assessment among Schemes, collaborate to enhance the practice of EQA including whenever possible to warrant traceability of EQAS to primary standards.
Keywords: Occupational and environmental laboratory medicine; Equivalence of assessment; Traceability; Uncertainty
Quality specifications for evaluation and comparison of performance among external quality assessment schemes in occupational and environmental laboratory medicine by Andrew Taylor; Jurgen Angerer; Josiane Arnaud; Françoise Claeys; Robert L. Jones; Olav Mazarrasa; Eric Mairiaux; Antonio Menditto; Patrick J. Parsons; Marina Patriarca; Alain Pineau; Sinikka Valkonen; Jean-Philippe Weber; Cas Weykamp (pp. 440-445).
Quality specifications (QS) are proposed for lead in blood and for aluminium, copper, selenium and zinc in serum as part of the aim to set standards of performance for laboratories so that results can be demonstrated to be fit for the purpose to which they are applied. The QS were established taking account of the analytical state-of-the-art, physiological variations in the concentrations of the analyte and the clinical purpose for which the assay is to be used. A procedure was devised that uses these QS to give equivalence of assessment among external quality assessment schemes (EQAS), thus avoiding conflicting information which has been demonstrated in the past. Advantages of this procedure are: to provide direct comparison of performance of laboratories taking part in different schemes, to provide equivalence of assessment of laboratory performance necessary to establish mutual recognition agreements, and to demonstrate the fitness for purpose of results from participants.
Keywords: Quality specifications; Occupational and environmental laboratory medicine; Z-score; Equivalence of performance assessment; Fitness-for-purpose
Quality specifications for evaluation and comparison of performance among external quality assessment schemes in occupational and environmental laboratory medicine by Andrew Taylor; Jurgen Angerer; Josiane Arnaud; Françoise Claeys; Robert L. Jones; Olav Mazarrasa; Eric Mairiaux; Antonio Menditto; Patrick J. Parsons; Marina Patriarca; Alain Pineau; Sinikka Valkonen; Jean-Philippe Weber; Cas Weykamp (pp. 440-445).
Quality specifications (QS) are proposed for lead in blood and for aluminium, copper, selenium and zinc in serum as part of the aim to set standards of performance for laboratories so that results can be demonstrated to be fit for the purpose to which they are applied. The QS were established taking account of the analytical state-of-the-art, physiological variations in the concentrations of the analyte and the clinical purpose for which the assay is to be used. A procedure was devised that uses these QS to give equivalence of assessment among external quality assessment schemes (EQAS), thus avoiding conflicting information which has been demonstrated in the past. Advantages of this procedure are: to provide direct comparison of performance of laboratories taking part in different schemes, to provide equivalence of assessment of laboratory performance necessary to establish mutual recognition agreements, and to demonstrate the fitness for purpose of results from participants.
Keywords: Quality specifications; Occupational and environmental laboratory medicine; Z-score; Equivalence of performance assessment; Fitness-for-purpose
Proficiency testing in analytical chemistry, microbiology and laboratory medicine – working group discussions on current status, problems and future directions by Ellen van Berkel; Nick Boley; Steve Ellison; Jean-Claude Libeer; Irma Mäkinen; Sverre Sandberg; Dan Tholen; Barry Tylee; Cas Weykamp (pp. 446-450).
Working group (WG) discussions on proficiency testing and external quality assessment held at the Eurachem workshop, Portorož, Slovenia 26–27 Sept 2005 are summarised. The discussions focused on performance criteria (WG 1), different aspects of accreditation (WGs 2–3), the revised international harmonised protocol (WG 4), pre- and post-analytical schemes (WG 5), Internet applications (WG 6), experience from the CoEPT project (WG 7), and future aspects (WG 8). Current status, problems and future directions were identified. The WG contained a mix of participants with different expertise. This was done to promote cross-fertilisation of ideas between sectors. The WG issues reflected the content of the keynote lectures and some issues were covered from different perspectives by more than one WG.
Keywords: Proficiency testing; External quality assessment; Accreditation; Internet; Comparability; CoEPT
Proficiency testing in analytical chemistry, microbiology and laboratory medicine – working group discussions on current status, problems and future directions by Ellen van Berkel; Nick Boley; Steve Ellison; Jean-Claude Libeer; Irma Mäkinen; Sverre Sandberg; Dan Tholen; Barry Tylee; Cas Weykamp (pp. 446-450).
Working group (WG) discussions on proficiency testing and external quality assessment held at the Eurachem workshop, Portorož, Slovenia 26–27 Sept 2005 are summarised. The discussions focused on performance criteria (WG 1), different aspects of accreditation (WGs 2–3), the revised international harmonised protocol (WG 4), pre- and post-analytical schemes (WG 5), Internet applications (WG 6), experience from the CoEPT project (WG 7), and future aspects (WG 8). Current status, problems and future directions were identified. The WG contained a mix of participants with different expertise. This was done to promote cross-fertilisation of ideas between sectors. The WG issues reflected the content of the keynote lectures and some issues were covered from different perspectives by more than one WG.
Keywords: Proficiency testing; External quality assessment; Accreditation; Internet; Comparability; CoEPT
Calibration services in the frame of accredited coagulation EQA schemes – Meeting the IVD directive by Ulf Örnemark; Elisabeth Nilsson; Gunnar Nordin; Nils Egberg; Tomas L Lindahl; Andreas Hillarp; Lennart Stigendahl; Inger Fagerberg (pp. 451-454).
Organisers of external quality assurance programmes may, for various reasons, also manufacture in vitro diagnostic medical devices, or provide calibration services. This paper describes measures taken by a Swedish organiser to meet the requirements of the European Commission's directive 98/79/EC for a national calibration of prothrombin time. Quality management system requirements and interactions with coagulation experts are summarised.
Keywords: In vitro diagnostic medical devices; Calibration; External quality assessment; Coagulation
Calibration services in the frame of accredited coagulation EQA schemes – Meeting the IVD directive by Ulf Örnemark; Elisabeth Nilsson; Gunnar Nordin; Nils Egberg; Tomas L Lindahl; Andreas Hillarp; Lennart Stigendahl; Inger Fagerberg (pp. 451-454).
Organisers of external quality assurance programmes may, for various reasons, also manufacture in vitro diagnostic medical devices, or provide calibration services. This paper describes measures taken by a Swedish organiser to meet the requirements of the European Commission's directive 98/79/EC for a national calibration of prothrombin time. Quality management system requirements and interactions with coagulation experts are summarised.
Keywords: In vitro diagnostic medical devices; Calibration; External quality assessment; Coagulation
Measurement traceability and its role in proficiency testing schemes – a case study for wastewater analysis in Slovenia by Andreja Drolc; Magda Cotman; Milenko Ros; Nineta Majcen (pp. 455-461).
This paper reports how measurement traceability of results of field laboratories in the area of wastewater analysis can be demonstrated by participation in a proficiency testing scheme based on reference values. A description of the scheme, organized by the National Institute of Chemistry, Ljubljana, Slovenia, is given: preparation of test material, homogeneity and stability testing, reference measurements for establishing reference value and setting performance criteria for the participants. Reference values were obtained by validated methods, traceability to appropriate measurement references was established and measurement uncertainty was evaluated from combining uncertainty components. Results indicate that the majority of Slovenian laboratories analysing water operate under the appropriate traceability conditions. Laboratories participating in proficiency testing schemes that integrate metrological principles are able to demonstrate traceability to SI units and their measurement capability.
Keywords: Metrology in chemistry; Wastewater analysis; Ammonium nitrogen; Proficiency testing scheme; Traceability
Measurement traceability and its role in proficiency testing schemes – a case study for wastewater analysis in Slovenia by Andreja Drolc; Magda Cotman; Milenko Ros; Nineta Majcen (pp. 455-461).
This paper reports how measurement traceability of results of field laboratories in the area of wastewater analysis can be demonstrated by participation in a proficiency testing scheme based on reference values. A description of the scheme, organized by the National Institute of Chemistry, Ljubljana, Slovenia, is given: preparation of test material, homogeneity and stability testing, reference measurements for establishing reference value and setting performance criteria for the participants. Reference values were obtained by validated methods, traceability to appropriate measurement references was established and measurement uncertainty was evaluated from combining uncertainty components. Results indicate that the majority of Slovenian laboratories analysing water operate under the appropriate traceability conditions. Laboratories participating in proficiency testing schemes that integrate metrological principles are able to demonstrate traceability to SI units and their measurement capability.
Keywords: Metrology in chemistry; Wastewater analysis; Ammonium nitrogen; Proficiency testing scheme; Traceability
Chlorophyll-a determination: results of an interlaboratory comparison by Petra Schilling; Martin Powilleit; Steffen Uhlig (pp. 462-469).
A chlorophyll-a interlaboratory comparison was carried out to compare three different analytical chlorophyll-a determination methods: a German standard DIN 38412-16, a method of the HELCOM-Combine-Manual and the different “in-house” methods of participating laboratories. Eleven laboratories took part. They had to determinate the chlorophyll-a and phaeopigment content in two seawater samples taken from the Baltic Sea. Furthermore, for the assessment three different statistical evaluation methods were applied: the German standard DIN 38402-42, the Q-method combined with an estimator according to Huber and the Cofino-method. All analytical methods were appropriate to determine the chlorophyll-a content. The relative standard deviations of reproducibility for chlorophyll-a varied between 12 and 31%. None of the analytical methods was appropriate to determine the phaeopigment content quantitatively. The relative standard deviations of reproducibility for phaeopigments ranged between 87 and 158%. The applied statistical evaluation methods resulted in different assessments. The Q-method combined with an estimator according to Huber proved to be the best qualified method.
Keywords: Chlorophyll-a ; Cofino-method; Interlaboratory comparison; Marine monitoring; Phaeopigments
Chlorophyll-a determination: results of an interlaboratory comparison by Petra Schilling; Martin Powilleit; Steffen Uhlig (pp. 462-469).
A chlorophyll-a interlaboratory comparison was carried out to compare three different analytical chlorophyll-a determination methods: a German standard DIN 38412-16, a method of the HELCOM-Combine-Manual and the different “in-house” methods of participating laboratories. Eleven laboratories took part. They had to determinate the chlorophyll-a and phaeopigment content in two seawater samples taken from the Baltic Sea. Furthermore, for the assessment three different statistical evaluation methods were applied: the German standard DIN 38402-42, the Q-method combined with an estimator according to Huber and the Cofino-method. All analytical methods were appropriate to determine the chlorophyll-a content. The relative standard deviations of reproducibility for chlorophyll-a varied between 12 and 31%. None of the analytical methods was appropriate to determine the phaeopigment content quantitatively. The relative standard deviations of reproducibility for phaeopigments ranged between 87 and 158%. The applied statistical evaluation methods resulted in different assessments. The Q-method combined with an estimator according to Huber proved to be the best qualified method.
Keywords: Chlorophyll-a ; Cofino-method; Interlaboratory comparison; Marine monitoring; Phaeopigments
QUASIMEME results of laboratories involved in the German Marine Monitoring Programme for the North and Baltic Seas by Michael Gluschke (pp. 470-473).
This case study is written for laboratories in the German Marine Monitoring Program (GMMP) for the North and Baltic Seas in order to give support to the assessment of proficiency testing results for their external quality assurance. A second issue is to provide a practical, understandable and common way for the calculation of laboratory performance parameters, so-called combination scores. In this paper, the GMMP laboratory proficiency testing results of QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe) Laboratory Performance Studies for the last 5 years were reviewed. Combination scores for organochlorine pesticides and chlorinated biphenyls in marine sediment are presented and explained. However, the assessment approach is very general and should be applicable to most testing laboratories in the chemical field.
Keywords: Proficiency testing laboratory; Performance studies; Interlaboratory comparison; Combination scores; Z-scores; External quality assurance
QUASIMEME results of laboratories involved in the German Marine Monitoring Programme for the North and Baltic Seas by Michael Gluschke (pp. 470-473).
This case study is written for laboratories in the German Marine Monitoring Program (GMMP) for the North and Baltic Seas in order to give support to the assessment of proficiency testing results for their external quality assurance. A second issue is to provide a practical, understandable and common way for the calculation of laboratory performance parameters, so-called combination scores. In this paper, the GMMP laboratory proficiency testing results of QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe) Laboratory Performance Studies for the last 5 years were reviewed. Combination scores for organochlorine pesticides and chlorinated biphenyls in marine sediment are presented and explained. However, the assessment approach is very general and should be applicable to most testing laboratories in the chemical field.
Keywords: Proficiency testing laboratory; Performance studies; Interlaboratory comparison; Combination scores; Z-scores; External quality assurance
Estimates of uncertainty of measurement from proficiency testing data: a case study by Marina Patriarca; Ferdinando Chiodo; Marco Castelli; Antonio Menditto (pp. 474-480).
The results obtained by a laboratory over a number of proficiency testing/external quality assessment schemes (PT/EQAS) rounds can give information on the uncertainty of its measurements for a given test, provided that conditions such as full coverage of the routine analytical range, traceability, and small uncertainty of the assigned values (compared to the spread of the results) are met and provided that systematic deviations and any other sources of uncertainty are considered. As organisers of the Italian EQAS (ITEQAS) in occupational and environmental laboratory medicine, we tested this hypothesis using as model data from well-performing laboratories taking part in ITEQAS for lead in blood over the last 2 years. We also investigated how different PT/EQAS features (frequency of trials and number of samples) would affect a laboratory estimate of its uncertainty. Such information can be helpful in improving PT/EQAS organisation and define, for a given test: (a) the state of the art of the uncertainty of current measurement procedures, (b) identify needs for improvement of analytical methodologies and (c) set targets for acceptable uncertainty values.
Keywords: Uncertainty estimate; Lead in blood; External quality assessment; Uncertainty of assigned values
Estimates of uncertainty of measurement from proficiency testing data: a case study by Marina Patriarca; Ferdinando Chiodo; Marco Castelli; Antonio Menditto (pp. 474-480).
The results obtained by a laboratory over a number of proficiency testing/external quality assessment schemes (PT/EQAS) rounds can give information on the uncertainty of its measurements for a given test, provided that conditions such as full coverage of the routine analytical range, traceability, and small uncertainty of the assigned values (compared to the spread of the results) are met and provided that systematic deviations and any other sources of uncertainty are considered. As organisers of the Italian EQAS (ITEQAS) in occupational and environmental laboratory medicine, we tested this hypothesis using as model data from well-performing laboratories taking part in ITEQAS for lead in blood over the last 2 years. We also investigated how different PT/EQAS features (frequency of trials and number of samples) would affect a laboratory estimate of its uncertainty. Such information can be helpful in improving PT/EQAS organisation and define, for a given test: (a) the state of the art of the uncertainty of current measurement procedures, (b) identify needs for improvement of analytical methodologies and (c) set targets for acceptable uncertainty values.
Keywords: Uncertainty estimate; Lead in blood; External quality assessment; Uncertainty of assigned values