Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.16, #12)
The 4th international conference on metrology: measurement and testing in the service of society, 23–24 May 2011, Jerusalem, Israel
by Ilya Kuselman (pp. 597-598).
Warning: false sense of certainty from the illusion of accuracy and precision in measurements by Mayer Brezis (pp. 599-602).
The illusion of accuracy and precision in testing is often associated with overconfident safety checks before catastrophes: National Aeronautics and Space Administration (NASA) “no safety-of-flight issues,” Deepwater Horizon site in Gulf Mexico reported as “industry model for safety” a year before its explosion, and Fukushima nuclear plant safety test found “satisfactory” at seismic magnitude viewed highest possible. In health care, testing overuse and misuse play significant roles in overconfidence and mistakes. Gaps between systems are most susceptible to errors, such as in miscommunications between the laboratory and the clinic. A safety culture is characterized by ability to communicate, anticipation of misunderstanding and resilient learning from failures. The discussion will show how messages from the laboratory may reduce the false sense of certainty from a test result; how results of tests are meaningless without pre-test estimates; how multiplicity of routine tests increases chances of false positivity; and how reporting measurement limitations can educate all users, including laboratory technicians, clinicians and patients, about the importance of quality assurance and about the pervasive nature of uncertainty beyond analytical performance. In conclusion, an illusion of accuracy and precision in testing evokes among clinicians a false sense of certainty leading to overuse and misuse of tests. Messages from the laboratory may reduce overconfidence from test results and lead to safer use of testing.
Keywords: Overconfidence; Safety; Miscommunication; Errors; Gaps between systems; False security
Metrology in service of society: the role of proficiency testing by Daniel Tholen (pp. 603-605).
A sound system of competent measurements, underpinned by standards and accreditation, is an essential component of the infrastructure of any modern society. Proficiency Testing is an indispensible tool for developing and maintaining this infrastructure. It is used to verify compliance with standards, for ongoing monitoring of laboratory performance, for demonstration of competence, and for evaluating the performance of measurement procedures; it is used to indicate performance problems that might not be detected otherwise; and it is used as a tool for education and self-improvement. The new International Standard, ISO/IEC 17043, contains requirements and recommendations to make optimal use of this important tool.
Keywords: Proficiency testing; Metrology; Standards; Accreditation; ISO/IEC 17043
Metrological concepts required for food safety and quality testing by Franz Ulberth (pp. 607-613).
The safety of the food we consume has a direct impact on our well-being and is a determinant for the quality of life. Food testing and the metrological principles associated with this activity play a key role in helping to ensure the safety of the food chain. The globalisation of food trade and national as well as international food safety regulations has produced an enormous demand for comparability of analytical results independent of temporal or spatial borders. Measurement-related elements of EU food legislation and their practical implementation as well as analytical requirements derived from the Codex Alimentarius are discussed in this contribution.
Keywords: Food safety; Metrology; EU food legislation; Codex Alimentarius
Long-term stability study of drug products and out-of-specification test results by Ilya Kuselman; Ilana Schumacher; Francesca Pennecchi; Cathy Burns; Aleš Fajgelj; Paolo de Zorzi (pp. 615-622).
A metrological approach for investigating out-of-specification (OOS) test results in long-term stability study of drug products was used. It is shown that OOS test results can indicate an actual change in a measured property of a product or be metrologically related with a certain confidence probability, i.e., be caused by the measurement problems, while the product still meets the quality requirements at the time of testing. As examples, results of testing sodium chloride injections in 500-mL plastic containers and of epinephrine (l-adrenaline) injections in 1-mL ampoules were discussed. Regression analysis of the data was performed, as well as warning and action lines for shelf life of the products calculated for relevant measurement uncertainties and confidence probabilities. Producer’s and consumer’s risks of the established shelf life values were also estimated.
Keywords: Stability study; Regression analysis; Out-of-specification test results; Measurement uncertainty; Producer’s risk; Consumer’s risk
Quality assurance for molecular epidemiology of tuberculosis methods in the mycobacterium reference laboratory by Paul J. Freidlin; Drora Goldblatt; Hasia Kaidar-Shwartz; Zeev Dveyrin; Efrat Rorman (pp. 623-635).
In the National Mycobacterium Reference Laboratory of the Israeli National Public Health Laboratory (hereafter referred to as “the laboratory”), three methods are employed for the molecular epidemiology of Mycobacterium tuberculosis: IS6110 restriction fragment length polymorphism typing (RFLP typing), 43 spacer oligonucleotide typing (spoligotyping), and 24 loci Mycobacterial Interspersed Repeating Unit—Variable Number of Tandem Repeats typing (MIRU-VNTR typing). In this article, we describe the main practical aspects concerning quality assurance of these methods that are based on standardized, internationally agreed upon conditions, including consensus reference strains and markers. All three methods were validated by classical epidemiology (confirmed transmission) and clinical information. The laboratory has introduced a new 5 colors, 4 primer sets multiplex modification of the optimal 24-miru typing system that includes an easily produced in-house internal standard for the high-throughput capillary electrophoresis system. Quantitative measurement of the internal standards yielded statistics for measurement uncertainty that include the frequency distribution, mean, standard deviation, 95% confidence interval and coefficient of variation. Use of the new internal standard developed in our laboratory allowed us to introduce the first quantitative evaluation of the system performance of the AB3130xl capillary electrophoresis genetic analyzer for MIRU-VNTR typing. The results are discussed in terms of expected accuracy and precision of MIRU-VNTR results, and possible implications for forensic microsatellite typing which may be much more sensitive to the observed intra- and inter-plate variation.
Keywords: Restriction fragment length polymorphism; Spoligotyping; Mycobacterial interspersed repetitive units; Molecular epidemiology of tuberculosis; Quality assurance
Evaluation of measurement uncertainty components associated with results of radiochemical neutron activation analysis for determination of uranium traces by Ljudmila Benedik; Urška Repinc (pp. 637-642).
Being aware of the importance to consider every step in the evaluation of the combined measurement uncertainty of the result, the purpose of this work was to evaluate the contribution of the radial thermal neutron flux gradient to the uncertainty budget for trace level uranium determination in biological materials by a radiochemical neutron activation analysis (RNAA). Determination of uranium via the short-lived nuclide 239U was based on solvent extraction with TBP and measurement of the chemical yield from the gamma-ray spectrum of the isolated fraction via 235U. It has been shown previously, that radial neutron flux gradient, could have a relevant effect on the final result obtained by RNAA. In the present work, radial neutron flux gradient within the irradiation assembly generally accepted in our lab (standards tapped beside the sample), varied between 93 and 108% around the mean value and contributes approximately 20% to the combined measurement uncertainty of the result.
Keywords: Radial neutron flux gradient; Measurement uncertainty; Radiochemical neutron activation analysis; Uranium
Estimation of alert and change limits and its application in the plausibility control by María José Castro-Castro; Dolors Dot-Bach; Beatriz Candás-Estébanez; Ruth Cano-Corres; Xavier Fuentes-Arderiu (pp. 643-647).
In the clinical laboratory, one of the most objective ways to perform the final review of patients’ measured values is the use of computerized plausibility control (i.e., set of procedures used to decide whether a patient’s measured value is valid according to established clinical and biological criteria). This study is focused on the estimation of alert and change limits to be applied to detect doubtful patients’ measured values. These limits are useful to improve the final review of patients’ measured values since these limits are produced objectively and are selected according to the clinical laboratory needs, letting the clinical laboratory professional staff to save time and effort.
Keywords: Plausibility control; Validation of measured values; Alert limits; Change limits; Deltacheck
Generic division of ‘quantity’ and related terms by René Dybkaer (pp. 649-651).
In the slow evolution of the International vocabulary of metrology (VIM), the first concept of ‘quantity’ has now been divided generically into ‘ordinal quantity’ and a coordinate primitive without definition and term. An analysis of the concepts by their characteristics is made, and the nature of inheritance is discussed in response to a recent communication in this journal. A completion of the initiated generic division of ‘quantity’ is suggested, and a neoterm for the sister of ‘ordinal quantity’ is offered on the basis of two proposals.
Keywords: Characteristic; Generic division; Quantity; Term; Unitary quantity
Report on the 34th meeting of ISO/REMCO
by Hendrik Emons; John P. Hammond; Stéphane Sauvage (pp. 653-655).
Unresolved concerns about the “new SI”
by Jack Miller; Theodore P. Hill; Albert Censullo (pp. 657-658).