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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.12, #8)
The 3rd International Conference on Metrology: Trends and Applications in Calibration and Testing Laboratories, 14–16 November 2006, Tel Aviv, Israel
by Ilya Kuselman (pp. 389-390).
Implementation of proficiency testing schemes for a limited number of participants by Maria Belli; Stephen L. R. Ellison; Ales Fajgelj; Ilya Kuselman; Umberto Sansone; Wolfhard Wegscheider (pp. 391-398).
A metrological background for the selection and use of proficiency testing (PT) schemes for a limited number N of laboratories-participants (less than 20–30) is discussed. The following basic scenarios are taken into account: (1) adequate matrix certified reference materials (CRM) or in-house reference materials (IHRM) with traceable property values are available for PT use as test items; (2) no appropriate matrix CRM is available, but a CRM or IHRM with traceable property values can be applied as a spike or similar; (3) only an IHRM with limited traceability is available. The discussion also considers the effect of a limited population of PT participants N p on statistical assessment of the PT results for a given sample of N responses from this population. When N p is finite and the sample fraction N/N p is not negligible, a correction to the statistical parameters may be necessary. Scores suitable for laboratory performance assessment in such PT schemes are compared.
Keywords: Proficiency testing; Sample size; Population; Traceability; Measurement uncertainty
The use of multiple correspondence analysis for the evaluation of inter-laboratory comparisons by Miloslav Suchánek; Piotr Robouch; Yetunde Aregbe; Alejandro Herrero; Philip Taylor (pp. 399-403).
Participation in inter-laboratory comparisons (ILC) is one of the recommended means of external quality control according to ISO/IEC 17025:2005. Providers of ILC or proficiency test (PT) schemes collect, besides the measurement results on the test samples, information on the sample treatment and measurement procedure. The objective of this paper is to evaluate in a non-traditional way, using numerical and non-numerical data provided by the participants in IMEP-20 (trace elements in tuna fish), the additional information concerning the applied analytical methods and the accreditation/nomination status. Arsenic was taken as an example. The basic statistical procedure for the evaluation of questionnaire information was the multiple correspondence analysis (MCA). Univariate clustering techniques were applied for the categorization of the numerical data (measurement values). The methodology of the evaluation of supplementary non-numeric information used in this paper might serve (a) to providers of ILC (PT) schemes to modify/improve their questionnaires and (b) to give laboratories better guidance in the methods used for the determination of various analytes in different matrices. This paper is meant serve as a guide for the possible interpretation of the questionnaires accompanying ILC schemas.
Keywords: Inter-laboratory comparison; Correspondence analysis; IMEP
The accreditation system for Russian analytical laboratories and its development by I. V. Boldyrev; Yu. A. Karpov; V. I. Paneva (pp. 405-408).
The analytical laboratories accreditation system (SAAL) began its work in 1992. At first, SAAL was created for laboratories performing quantitative chemical analysis, but its activities have constantly expanded. SAAL presently covers laboratories determining oil and petroleum properties, properties of construction materials, parameters of dangerous and harmful industrial goods, precious stones, rubber, plastic, metals etc. Today, SAAL comprises over 3,000 accredited laboratories, 34 accreditation bodies and over 200 assessors united under the Federal Agency on Technical Regulating and Metrology. Within the Russian Federation, SAAL is recognized by various bodies and organizations as a reliable tool in the demonstration of technical competence of laboratories. This report is devoted to the history of SAAL, describing the separate stages of its development, evolution of its requirements for laboratories and accreditation procedures, the principles on which SAAL was based, and conformity of these principles to the legal requirements of the Russian Federation.
Unification of the quality assurance systems of public health laboratories conformed to ISO 17025, ISO 15189, and ISO 9000: a major organizational change by Haim Hacham; Nurit Tetro; Salit Kochavi-Azolai; Nava Stern; Dana Mizrahi; Anna Lisenker; Emanuel Gazit (pp. 409-413).
The Department of Public Health Laboratories consists of five major laboratories located across the country of Israel: four environmental laboratories performing microbiological and chemical testing of food and water products [accredited according to International Organization for Standardization (ISO) 17025 since 1999) and a fifth laboratory that is dedicated to virology testing (certified according to ISO 9000 since 2003). Historically, each laboratory operated independently and developed its own quality assurance (QA). On November 2004, an important strategic decision was made: to unify all five laboratories’ QA systems conformed to ISO 17025, ISO 15189, and ISO 9000—a transition from five laboratories operating independently in the field of QA toward establishing a multisite laboratory. This process was considered and visualized as a major organizational change and therefore raised some resistance among both QA managers and the professional laboratories’ management. Thus, it was necessary to overcome the resistance and at the same time induce thoughts of ways of reshaping and formatting the new and uniform quality manual and uniform standard operating procedures (SOPs). In September 2005, the first phase of the process was completed, and all four environmental public health laboratories successfully passed a reaccreditation audit using a uniform QA manual guide and partially uniform SOPs. We shall share our experience and discuss the major contributions of this process to overall laboratory management.
Keywords: Organizational change; Quality Assurance Unification; Uniform SOPs
A way of establishing quality of measurements in gas analysis—national and international aspects by Mykhaylo Rozhnov; Ovsiy Levbarg (pp. 415-417).
Standardising quality of measurements at both the national and international level results in a unity in measurement that may be regarded a synonym of traceability. In gas analysis, the key issue in achieving this aim is production of gaseous reference materials. Establishing a network of secondary measurement standards at gaseous CRM producers’ sites in Ukraine might be interesting for those involved in gas analysis activities. Inevitably, problems concerning the recognition of measuring capabilities of both national metrological institutes and local CRM producers are now an international issue. Thus, the problems of national adoption of international standards, as well as harmonisation between different international documents are currently relevant, and Ukrainian experience may be useful to others in this field.
Keywords: Gas analysis; Traceability; Calibration gas mixtures; Measurement standards
Accuracy of single measurements by Semyon G. Rabinovich (pp. 419-424).
Single measurements are widely used in industry, trade and science, yet the problem of the estimation of the accuracy of this type of measurements is neither addressed nor even recognized in traditional Metrology. In particular, the Guide to the Expression of Uncertainty in Measurement is devoted to multiple measurements only and does not mention single measurements. This paper studies the problem of estimating the inaccuracy of single measurements and describes solutions to this problem. The proposed methods are based on metrological characteristics of measuring instruments rated in accordance with Recommendation R34 of International Organization of Legal Metrology (OIML). These characteristics are usually given in manufacturer certificates or provided by calibration laboratories. This paper treats single measurements as the basic type of measurement and multiple measurements as sets of successive single measurements.
Keywords: Single measurement; Measuring instrument; Inaccuracy; Uncertainty; Limits of error
Repeatability: some aspects concerning the evaluation of the measurement uncertainty by Matthias Rösslein; Sergio Rezzonico; Roman Hedinger; Marco Wolf (pp. 425-434).
Various publications stress the importance of the repeatability (i.e. precision) of the calculation of the measurement of uncertainty. We reveal by detailing an example from production control in the pharmaceutical industry that the effect of other influence quantities should not be neglected, because their magnitude is even larger than the contribution of repeatability. We review the role of repeatability within the calculation of measurement uncertainty for several common validation and day-to-day measurement scenarios. They show that measurement models need to consider the measurement sequences of the various scenarios. Otherwise the size and effect of the repeatability might be overestimated. At the end Monte Carlo simulations were used to investigate the determination of the repeatability under certain restrictions. The simulation uncovered a significant bias toward the common formula for calculating the standard deviation when it is based on a duplicated measurement of a sample.
Keywords: Measurement uncertainty; Repeatability; Standard deviation; Production control
Meeting the need for intercontinentally understood concepts and intercontinentally agreed terms for Metrology in Chemistry (at the occasion of the 2007 edition of the VIM) by Paul De Bièvre (pp. 439-442).
The need for intercontinentally understood concepts and intercontinentally agreed associated terms is demonstrated by some salient examples.
Keywords: Metrology in Chemistry; Concepts in metrology; Terms in metrology; Traceability; Comparability