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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.5, #3)
Proficiency testing schemes for polytechnic students: an educational project in The Netherlands by W. Oussoren; R. Visser (pp. B114-B118).
In the August 1999 issue of Accreditation and Quality Assurance reference was made to proficiency testing schemes organised for students at polytechnics in The Netherlands. The present paper describes in more detail this educational project which aims at increasing students' awareness of quality assurance and quality control (QA/QC) at polytechnics. The project has to be seen in relation to other regular activities to educate and train students and to prepare them for working in an analytical laboratory. This combined effort should result in well-educated and well-trained students with the right attitude to analytical work and to QA/QC. The project was organised under the auspices of the Working Group "Quality Assurance in Laboratory Education" (KILO).
Keywords: Key words Quality; Proficiency testing scheme; Education; Polytechnics
Evaluation of uncertainty utilising the component by component approach by M. Rösslein (pp. 88-94).
This paper reviews the so-called "component by component approach" of evaluating measurement uncertainty. An overview of the evaluation process is given followed by an in-depth discussion of some of the differences between this approach and the approach of utilising validation data. Some of the advantages and disadvantages of using the component by component approach are outlined at the end.
Keywords: Key words Uncertainty; Component by component approach; Evaluation of measurement uncetrtainty; Measurement uncertainty
Evaluation of uncertainty of reference materials by J. Pauwels; A. van der Veen; A. Lamberty; H. Schimmel (pp. 95-99).
Certification of reference materials is far more than just characterisation of a selected homogeneous batch of material. From the perspective of the ISO Guide on the Expression of Uncertainty in Measurement (GUM) all uncertainty sources relevant to the user of an individual certified reference material (CRM) sample at a moment in time should be part of the CRM uncertainty. This not only includes the full uncertainty of the batch characterisation (rather than the statistical variation), but also all uncertainties related to possible between-bottle variation, instability upon long-term storage and instability during transport to the customer.
Keywords: Key words Certified reference materials; Uncertainty; Characterisation; Uncertainty analysis
Assessment of permissible ranges for results of pH-metric acid number determinations using uncertainty calculation by I. Kuselman (pp. 100-103).
An approach to assess the permissible ranges for results of replicate determinations using uncertainty calculation is discussed. The approach is based on the known range distribution for normalized "range/standard deviation" values, which is equivalent to the distribution of the range for normalized results of replicate determinations having an average of 0 and a standard deviation of 1. It is shown that the permissible ranges can be assessed using tabulated percentiles of this distribution and calculated values of the determination (analysis) standard uncertainty. When the standard uncertainty calculation is performed before the analytical method validation, the permissible ranges can be predicted. As an example, the range is predicted for a new pH-metric method for acid number determination without titration in petroleum oils (basic, white and transformer). The results of the prediction are in good conformity with the experimental data.
Keywords: Key words Range; Prediction; Uncertainty of measurements; Analytical method validation; Acid number determination; pH-metry
The evaluation of measurement uncertainty from method validation studies by V. J. Barwick; S. L. R. Ellison; M. J. Q. Rafferty; R. S. Gill (pp. 104-113).
A protocol has been developed illustrating the link between validation experiments and measurement uncertainty evaluation. The application of the protocol is illustrated with reference to a method for the determination of three markers (CI solvent red 24, quinizarin and CI solvent yellow 124) in fuel oil samples. The method requires the extraction of the markers from the sample matrix by solid phase extraction followed by quantification by high performance liquid chromatography (HPLC) with diode array detection. The uncertainties for the determination of the markers were evaluated using data from precision and trueness studies using representative sample matrices spiked at a range of concentrations, and from ruggedness studies of the extraction and HPLC stages.
Keywords: Key words Measurement uncertainty; Method validation; Precision; Trueness; Ruggedness; High performance liquid chromatography
CERM – 2 : 2nd Regional Central European Conference on Reference Materials
by P. Mader; J. Táborský (pp. 118-119).
EURACHEM – the first 10 years by A. Williams (pp. 121-123).
Part 1 of the history of EURACHEM deals with the development of the initial idea and the early consultations within Europe that led to the definition of its aims and objectives, culminating in its formal establishment in July 1989. This was followed by the signing of the Memorandum of Understanding by 16 countries at the end of 1990. Part 2 describes the subsequent developments.
Keywords: Key words EURACHEM; History of EURACHEM