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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.12, #5)
Combining mistake-proofing and Jidoka to achieve world class quality in clinical chemistry by Clifford Martin Hinckley (pp. 223-230).
Extensive data demonstrates that the quality impact of automation is often disappointing, and may be no better than manual operations in many cases. When automated equipment is not set up or operated properly, large quantities of non-conformances are generated, which must be considered in the overall quality performance. Consequently, achieving the best results with automated equipment requires extensive use of mistake-proofing. Furthermore, unless we understand what to automate and the best method of automation, significant resources will be wasted, with disappointing results. Jidoka (the Japanese word for Automation with a Human Touch) provides key insights into the best attributes of automation.
Keywords: Automation; Mistake-proofing; Jidoka
Robust estimates of the theoretical standard deviation to be used in interlaboratory precision experiments by Peter-Th. Wilrich (pp. 231-240).
Interlaboratory experiments often contain results that strongly deviate from other results obtained in the same laboratory under repeatability conditions, or laboratory means that strongly deviate from other laboratory means. In ISO 5725-2 [1] and IUPAC [2], the basic standards for the organisation and analysis of interlaboratory experiments for the determination of precision of a measurement method, outlier tests are performed in order to detect such situations and to finally decide whether these values are retained in the analysis or discarded as outliers. This outlier treatment, which always has a subjective aspect, becomes unnecessary by using robust estimates of the repeatability and reproducibility standard deviation. This paper proposes to use Rousseeuw’s Q n as an extremely robust and efficient estimate of the standard deviation. Two examples show the performance of the new method.
Keywords: Interlaboratory experiments; Measurement methods; Precision; Repeatability; Reproducibility; Robust statistical methods
A new quality control material for marine environmental analysis by Amaia Guevara-Riba; Angels Sahuquillo; Roser Rubio; Gemma Rauret (pp. 241-248).
The implementation of the European Water Framework Directive (WFD) and of the sediment-quality criteria related to the potential disposal of dredged materials is expected to involve a substantial increase in the number of chemical analyses performed in marine environmental control laboratories. The chemical characterization of sediments (metals, elemental composition, etc.) and the potential release of metals under changing environmental conditions are relevant when dealing with risk assessment. The present paper describes the preparation of a quality control material (QCM) harbor sediment carried out in a specifically equipped laboratory at the University of Barcelona. The results of homogeneity and stability studies for total metal content (Cd, Cr, Cu, Ni, Pb, and Zn), extractable metal following the BCR three-step sequential extraction procedure (BCR-SEP), and total carbon content show the suitability of QCM for multi-parameter routine quality control (QC) in marine environmental laboratories.
Keywords: Quality control material; Harbor sediment; Heavy metals; Organic elemental analysis; Sequential extraction procedure
First proficiency test for the determination of NORM in contaminated soil from the oil field by Mohammad Saied Al-Masri; Abdul-aziz Aba (pp. 249-256).
The Atomic Energy Commission of Syria (AECS), in cooperation with the Arabic Atomic Energy Agency (AAEA), has initiated the first proficiency test exercise for the determination of naturally occurring radioactive materials (NORM) in contaminated soil from the oil field. The soil sample was collected from one of the most highly radioactively contaminated lagoons with production water in the Syrian oil fields, which was then prepared, characterised and certified according to a standard procedure. Samples were dispatched to laboratories from eight Arab countries; Kuwait, Egypt, Yemen, Tunisia, Jordan, the Kingdom of Saudi Arabia, Libya and Syria. The results were evaluated using three statistical criteria; z-score, the U test score and the relative bias. These statistical methods were used to evaluate the performance of each laboratory, in addition to the overall evaluation for each radionuclide. This evaluation has indicated that 57% and 86% of the results passed the criteria set for precision and accuracy applied for this test in relation to 226Ra and 228Ra, respectively. These two radionuclides are considered to be the most important radionuclides in the oil industry.
Keywords: Radium-226; Soil; Reference sample; Proficiency test; Oil industry
Validation of the HS-GC-FID method for the determination of ethanol residue in tablets by Magdalena Michulec; Piotr Konieczka; Jacek Namieśnik (pp. 257-262).
This paper describes the validation of a HS-GC-FID method (based on the Pharmacopeia’s method) for the determination of ethanol content in tablets. A general view of the procedure development/optimization process is presented. The main point of this study is the calculation of validation parameters. Selectivity of the method was determined. Linearity (r > 0.997) was observed in the range from 9.0 to 3,040 μg of ethanol per sample (because the mass of the tablets used was around 200 mg, this corresponds to 45–15,200 μg g−1). The method showed good recoveries (average 99.0%), and a relative standard deviation for repeatability and intermediate precision of 4.5% and 5.5% respectively. The limit of detection was calculated to be 3.0 μg of ethanol per sample (15 μg g−1). The uncertainty budget was done according to the "Guide to the Expression of Uncertainty in Measurement" (GUM)[1], and a relative expanded uncertainty was estimated as 4.8%.
Keywords: Validation; Pharmaceuticals; Solvent residues; Ethanol; Gas chromatography; Headspace analysis
Comments on the editorial "On quality of a measurement result" by Jan S. Krouwer (pp. 263-264).
A recent editorial reviewed several definitions of quality. The limitations of these definitions are discussed here, with a simple suggestion to define quality as meeting a specified error rate whereby the required elements for an error rate are listed.
Keywords: Quality; Error rate; Severity; Measurement uncertainty; Survey; Customer satisfaction
Update on COMAR: the Internet database for certified reference materials by Thomas Steiger; Rita Pradel (pp. 265-268).
This paper describes the COMAR database for certified reference materials (CRMs). The Web-based version of COMAR is freely accessible via the Internet. COMAR was established to assist laboratories in finding the CRMs needed. The database is maintained in a collaboration of the world’s major CRM producers. The planned changes in the database as agreed at the last COMAR council meeting in Prague in May 2006 are indicated.
Keywords: COMAR; Database; Reference materials; Certified reference materials
Reply to “Use of participant EQA results to assess sample homogeneity and stability for qualitative analytes” (Tholen et al.)
by Kris Vernelen; Jean-Claude Libeer (pp. 273-274).