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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.15, #2)
On ‘trueness control materials’, better known under the multi-purpose term of ‘Certified Reference Materials’ (CRMs)
by Paul De Bièvre (pp. 71-72).
The role of proficiency testing in method validation (pp. 73-79).
The general principle of using data collected during proficiency testing (PT) for the additional purpose of assessing method performance is discussed. Particular attention is paid to the similarities and differences in conduct of traditional interlaboratory method performance studies and proficiency testing. Recommendations are made for implementing PT-based method performance studies, including statistical assessment of the data. It is concluded that, properly implemented, PT-based method performance study provides essentially equivalent information to that obtained from traditional collaborative study and may be used in appraising candidate methods with a view to their adoption as standard methods.
Keywords: Proficiency testing; Validation; Inter-laboratory study; Collaborative study
Certification of a pure reference material for the ginsenoside Rg 1 by Dal-Ho Kim; Jin-Kyu Chang; Hyun-Joo Sohn; Byong-Gu Cho; Sung-Ryong Ko; Kil-Bong Nho; Dae-Sig Jang; Sang-Myung Lee (pp. 81-87).
A pure certified reference material (CRM) for the ginsenoside Rg 1 was prepared from roots of Panax ginseng by extraction and separation of ginsenosides. The mass fraction of the main component (ginsenoside Rg 1 ) in the reference material was determined and its uncertainty was assessed from various input quantities, such as organic impurities, residual moisture, residual solvent, ash, and insoluble matters. To measure these input quantities, HPLC/CAD, Karl Fischer (KF) coulometry, gravimetry, and GC/FID were used. Homogeneity and long-term stability of the reference material are discussed. The certified mass fraction of Rg 1 in the reference material is 0.974 ± 0.006 (k = 2) with a shelf life of 1 year.
Keywords: Ginsenoside; Panax ginseng C.A. Meyer; Purity; CRM; HPLC/CAD; Karl Fischer titration; Gravimetry; Ash; GC/FID
Establishing a quality assurance plan for nucleic acid-based diagnostic laboratories: from planning to implementation by Derliane Oliveira; Sook Fan Yap; Siripan Wongwanich; Baldip Khan; Juan Cristina (pp. 89-97).
Nucleic acid-based technologies have opened new perspectives in diagnosis, prognosis, and treatment in clinical medicine. To maintain patient confidence in this rapidly expanding field and to provide the highest standard of analysis, strict laboratory quality assurance procedures must be followed. While impressive break-through are taking place in this field, the need for an appropriate and suitable quality assurance (QA) plan for nucleic acid-based diagnostic laboratories must be a top priority. In this study, we developed a systematic QA plan for this kind of diagnostic laboratories that would enable us to assure the highest quality standards of their services. We focus on those labs that would like to start introducing a quality system for the first time and discuss the most appropriate ways to pave the way to implement a QA plan from the beginning. This QA plan is suitable for any nucleic acid-based techniques laboratory regardless of the field or services provided.
Keywords: Nucleic acid; Diagnosis; Quality assurance; Clinical medicine; Laboratory management
Comparison of international standards concerning the capability of detection for analytical methods by L. Brüggemann; P. Morgenstern; R. Wennrich (pp. 99-104).
The international standard ISO 11843 specifies the experimental conditions for the estimation of critical values of analytical methods referring to the capability of detection. The present paper aimed at a formal comparison of the ISO 11843 standard with the German standard DIN 32645 and the Commission Decision 2002/657/EC of the EU. In this context the particular scope of each standard is discussed based on a numerical example given in the DIN standard. For practitioners a better understanding of the different guidelines based on the same basics, i.e. the statistical theory of hypothesis testing and the probabilities of false positives α and false negatives β, is to be achieved.
Keywords: Capability of detection; Critical concentrations; Performance criteria
Estimating the decision limit and the detection capability using matrix-matched calibration data by Panagiotis Steliopoulos (pp. 105-109).
Matrix-matched calibration allows to quantify accurately without the necessity of correcting results for the bias error caused by matrix effects. In this work, an approach to estimate the decision limit CCα and the detection capability CCβ using matrix-matched calibration data series that were obtained at different times and under different conditions is described. The basic idea underlying the approach is to consider the set of the calibration submodels to be an ensemble of equally probable events. By way of illustration, the methodology is applied to a data set acquired within a validation study of an LC–MS assay for the determination of the aminoglycoside antibiotic dihydrostreptomycin in kidney.
Keywords: Decision limit; Detection capability; Commission Decision 2002/657
Study of quality control and metal distribution in urban airborne particulates by Sugandha D. Garway; Sahdeo R. Bhaisare; Dattatraya G. Garway; Girish Himatlal Pandya (pp. 111-118).
In this investigation, results of 33 elements in airborne samples collected continuously over nine urban locations are discussed. Inductively coupled plasma-atomic emission spectrometry technique was used for determining concentration of metals. Quality control was established prior to analysis of real air samples. The guidelines followed are based on USEPA Compendium Method IO-3.4. Uncertainty in analysis was also established. Based on the concentration of metals in airborne particulates, we attempted to study the metal distribution characteristics in ambient air at various urban locations. Metals such as Al, Ca, Fe were comparatively at higher concentrations than the other elements under study at most of the locations. The city vehicles operate on lead-free fuels; however, concentration of lead in urban dust was observed in the concentration range of 0.33–6.24 μg/m3. Soil samples were also collected from sites close to the air sampling locations. Soil samples were also analysed for metal content. Enrichment factor was determined for elements measured at nine urban locations. The data supports interpretation of results in terms of contribution of metals in airborne particulates from anthropogenic and noncrustal origin.
Keywords: Metals; Inductively coupled plasma-atomic emission spectrometry; Uncertainty; Enrichment factor; Quality control
Quality control of uranium concentration measurements by Aditi Chakrabarty; S. Mohapatra; R. M. Tripathi; V. D. Puranik; H. S. Kushwaha (pp. 119-123).
Quality assurance and quality control are necessary to ascertain the output of any instrument with a certain level of confidence and maintain the measurement process in a state of statistical control. Data generated by three laser fluorimeters, used for analysing mass concentration of total uranium in liquid samples, were used in the present study. Erroneous data values, called outliers, were detected by Dixon test, Discordance outlier test, Rosner outlier test and Box plot. The distribution fitted to the data, was tested by Kolmogorov–Smirnov test, Chi-square test and Shapiro–Wilks test. From Shewart Control Charts it was concluded that the instruments were not in statistical control and an instrumental problem existed. The instrumental problem was solved and the instruments were subjected to quality control exercise again. Statistical parameters of the data from the detectors were compared before and after servicing. The improvement of the quality of detector output was evident.
Keywords: Quality control; Outliers; Distribution fitting; Control charts
Regional cooperation in proficiency testing: strategy planning and practical experiences in Western Balkan countries by Janko Drnovšek; Igor Pušnik; Jovan Bojkovski; Gaber Begeš (pp. 125-131).
The article describes the project of regional cooperation in proficiency testing within CARDS 2006 (assistance programme to the Western Balkans), which was coordinated by European Committee for Standardization, European Commission and European Free Trade Association and conducted by the University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality. The later is the holder of the national standard for thermodynamic temperature as well as an accredited proficiency testing provider and also accredited as a calibration, testing and inspection laboratory. It is also responsible for graduate study programme Quality Engineering. Proficiency testing was considered as a core activity of the entire project, but additionally as a very appropriate platform for knowledge transfer of EU technical legislation in selected sectors, metrology, testing and quality assurance in general. The project had a high added value for participating laboratories in countries of Western Balkans, because it required an active role of all participating laboratories, assured participation of staff from national metrology institutions, all national accreditation bodies, and was supported by national quality infrastructures, such as standardization, governmental institutions etc. in the entire Western Balkans region. The activities stimulated progress in the area of conformity assessment, added knowledge to the implementation of technical directives and development of the technical part of national legislation and therefore facilitated the process toward the accession to the European Union. The main objective was therefore to organize proficiency testing in those sectors (construction, consumer protection and environment) that were vital in the pre-accession process of countries seeking full implementation of EU technical legislation.
Keywords: Proficiency testing; Regional quality infrastructure; EU technical legislation; Conformity assessment; Measurement and testing
The importance of cooling of urine samples for doping analysis by J. Gijs Kuenen; Wil N. Konings (pp. 133-136).
Storing and transporting of urine samples for doping analysis, as performed by the anti-doping organizations associated with the World Anti-Doping Agency, does not include a specific protocol for cooled transport from the place of urine sampling to the doping laboratory, although low cost cooling facilities can easily be made available. As a result, microbial and thermal degradation of the chemical substances in the urine may occur, which may lead to false negative or false positive results in the subsequent doping analysis. This scientifically and morally unacceptable practice is still maintained in spite of publications demonstrating that immediate cooling is an absolute requirement. Given the enormous societal consequences of positive tests, the lack of a controllable chain of custody during transport should be outlawed. This paper proposes a simple method, based on immediate cooling and cooled transport, which can easily be implemented in developed countries at low cost.
Keywords: Urine analysis; Bacterial contamination; Doping analysis; Anti-doping organization