Accreditation and Quality Assurance最新文献

Paul De Bievre interacted with the Australian national measurement system in the 1990s as it developed its chemical measurement system infrastructure. It was a fruitful and stimulating time when practical measurement—weights and measures in its modern forms—mixed with the ideas of metrology in chemistry. Among the issues discussed were accreditation, a new journal called accreditation and quality assurance (this journal, ACQUAL), clear and accurate communication in measurement, primary methods of measurement and basic principles of metrology in chemistry. I end commenting on the applicability of the practical metrology in chemistry perspective to the development of an international trading system in carbon and its credits: the weights and measures problem of the twenty-first century.

The role of silver–silver chloride electrode for providing the reference potential is quite important for the precise potentiometric measurements. Our study focuses to find the conditions for its optimal use, especially, in perspective for a long-term viability of electrode. In particular, we reassessed the temporal stability of the standard potential and presented the results of its measurement for a time span of ten years.

Glassware cleaning is an essential part of pharmaceutical industry’s quality process, although, to date, no precise methodology is recommended by the pharmaceutical regulations. This study focuses on developing a detailed validation procedure for laboratory glassware cleaning and applying it routinely in quality control labs. The first step was the determination of the worst-case among raw materials controlled on a pharmaceutical site by using the failure mode effects analysis (FMEA) approach based on water solubility (WS), flask volume (FV), concentration (C), detectability (D) according to the absorptivity, and the probability (P) of the occurrence of the risk based on raw material analysis frequency. The adopted manual cleaning method was validated on three series of six flasks. Absorbances at λ_max of cleaned and worst-case flasks were compared to the limit of detection (LOD). Methylparaben was found to be the worst-case. Cleaning validation was carried out on 50 mL flasks containing aqueous solutions at 0.11 g/L after a contact time of 20 min under stirring. A prewash with tap water, a proper wash with a 95-V/5-V water/detergent solution (quaternary ammonium), and a final wash with purified water were carried out. The absorbances of all the cleaned flasks were lower than those of the worst-case LOD (< 0.0112). The selected cleaning procedure has been successfully validated. The proposed approach precisely describes the steps to be followed and can be adapted by other pharmaceutical industries as part of their laboratory glassware cleaning validation methodology.

The measurement of alcohol concentration in exhaled air is used worldwide for sobriety checks by police and other services. Breath alcohol analyzers are instruments for the determination of alcohol (ethanol) mass concentration in exhaled air. These instruments are evaluated and calibrated in many countries (among others in Poland) using wet gas standards produced in situ from aqueous standard solutions in breath simulators. The value of the mass fraction of ethanol in the solution is necessary to determine the concentration of ethanol in the produced gas standard. New reference materials of ethanol in an aqueous solution intended for use in breath simulators for calibration and testing of breath alcohol analyzers were developed as a result of the Central Office of Measures (GUM) participation in the EMPIR 16RPT02 ALCOREF project. CRMs were certified following standard ISO 17034:2016 and ISO Guide 35:2017 ensuring traceability of certified values to SI units and covering ethanol content ranging from 0.129 g/kg to 5.051 g/kg required by OIML R126. The certified mass fractions of the ethanol and expanded uncertainties (k = 2) of the four reference materials representative for the entire range were (0.2588 ± 0.00040) g/kg (GUM 12.2), (0.6470 ± 0.00074) g/kg (GUM 12.3), (1.0352 ± 0.0014) g/kg (GUM 12.4) and (5.0506 ± 0.0092) g/kg (GUM 12.8). The CRMs produced by the procedure presented in this paper have been found to be fit for purpose.

This paper reviews some proficiency testing (PT) programmes operated under the auspices of Asia Pacific Metrology Programme and Asia Pacific Laboratory Accreditation Cooperation Joint Proficiency Testing Working Group. The assigned values of these joint PTs are traceable to the SI. Provision of PTs based on reference values (PTRVs) with metrological traceability enables meaningful performance evaluation and assessment of metrological comparability of the participants’ results. Special focus will be given to those joint PTs related to analysis of inorganic elements in various sample matrices organized or co-organized by Government Laboratory of Hong Kong, China. Comparison based on different evaluation criteria (i.e. consensus value vs reference value) is carried out. Comprehensive evaluation and review of some performance indicators revealed several crucial findings such as the performance of different analytical conditions, recent analytical trends and areas of improvements. The organization of a series of these joint PTs could be regarded as a strong support of the concept that PTRV with metrological traceable reference values is an effective way to promote the concept of metrological traceability to the field laboratories and provide a meaningful performance evaluation tool for assessment of PT performance.

Limited information was available on the quality and safety profile of tea in China, even though food quality and safety of tea is an issue of great concern to consumers and the public. Stochastic Bayesian modeling was employed in this study to investigate food quality and safety profile of tea in China market. Results indicated that the overall nonconforming rate (95 % CI, confidence interval) of tea was 2.6 ‰ (1.3 ‰ to 4.5 ‰), indicating a high level for the quality and safety status of tea in market. Pesticide residues exceeding maximal limit (MRLs) was the major cause leading to nonconformity of tea, with estimated incidences (95 % CI) of 11.7 ‰ (0.5 ‰ to 53.2 ‰), 1.1 ‰ (0.4 ‰ to 2.0 ‰), 2.3 ‰ (0.6 ‰ to 5.5 ‰), and 0.55 ‰ (0.06 ‰ to 1.51 ‰), respectively, for Yellow tea, Green tea, and Oolong tea; whereas illegal application of additives was more likely to occur in black tea, with an incidence of 1.1 ‰ (0.4 ‰ to 2.7 ‰), despite that an estimated incidence of 2.9 ‰ (0.4 ‰ to 16.1 ‰) was generated for Yellow tea due to fewer inspects and small sample sizes involved for analysis. The difference in quality and safety status of tea between provinces was statistically insignificant, as indicated by overlapped 95 % CIs of nonconforming rates. Results of this study provided reliable information on quality and safety profile of tea in China market, and suggested that application of pesticides during tea plantation and illegal use of additives during black tea production worth more attention in respect of quality and safety of tea.

The use of certified reference materials (CRMs) is essential for laboratories that want to achieve reliable results because these materials have well-defined property values that enable the traceability of certain parameters in several areas. The production of CRMs for microbiological tests is complex, as there is a natural instability of microorganisms. The objective of this study was to establish Cryptococcus neoformans and Cryptococcus gattii as CRM, according to the requirements of ISO 17034. The availability of these materials will assist in the cryptococcosis diagnosis and support the academic community, since cryptococcosis is among the most lethal mycoses and affects more than one million people worldwide each year. C. neoformans CFRVS CRM 40,323 and C. gattii CFRVS CRM 40,324 batches, in skim milk at 20 %, were homogeneous and stable for 1 year. The materials were also stable at 4 °C, 25 °C and 35 °C, temperatures that simulate transportation conditions, for 7 days. In addition to the quantitative characterization, qualitative characterization of materials was conducted by observing melanin production, l-Canavanine Glycine Bromothymol Blue (CGB) Agar test and by RFLP-URA5 analyses. Certified property values and their associated uncertainties were assigned for each CRM. For C. neoformans CFRVS CRM 40,323, expanded uncertainty (U_CRM) was 13 CFU mL⁻¹ for 33 CFU mL⁻¹ property value. For C. gattii CFRVS CRM 40,324, U_CRM was 9.2 CFU mL⁻¹ for 15 CFU mL⁻¹ property value. Our study contributes to the development of CRM production in the microbiological field, whose supply is still very limited worldwide.

Electrolytic conductivity is recognized as one of the parameters to determine water quality. An accurate measurement of electrolytic conductivity of wastewater before dumping it into the environment is crucial to prevent water pollution. Therefore, the ability of laboratories in conducting accurate and comparable measurements of electrolytic conductivity is important to guarantee the measurement results. The measurement quality of the laboratories can be determined by participating in a proficiency testing (PT) conducted by accredited PT provider. In 2018, Chemical Metrology Laboratory, Indonesian Institute of Sciences (LIPI), as a PT provider, conducted a PT for electrolytic conductivity measurement with synthetic wastewater as the PT test item. It was prepared from cations and anions commonly found in natural wastewater. A total of 25 participants from Indonesian testing laboratories reported their electrolytic conductivity measurements. These results were then evaluated using a standardized performance statistic of z score, z′ score, E_n score and ζ (zeta) score. There were 20 laboratories having satisfactory results evaluated using both z score and z′ score, while only 14 laboratories were considered having a successful performance evaluated using E_n score and ζ score. The evaluation results show that the participants already have the ability to measure the electrolytic conductivity value but some of them still need improvement in estimating the uncertainty.

The Guide to the Expression of Uncertainty in Measurement (GUM) provides a framework for evaluating analytical data and characterizing their dispersion in a consistent manner. This is of eminent importance in the case of reference materials and their recommended values that are used for calibration of further measurements. The proper propagation of uncertainties for those data is essential. Guidance is provided in the GUM on how to calculate the combined standard uncertainty for a mean value or central value based on multiple individual measurements including their calibration uncertainty. However, according to published data, the guidance provided by GUM is not always properly applied in practice. Several published studies show calculated uncertainties much lower than those of input quantities. This may be caused by improper handling of the propagation of uncertainty components, thereby breaking the traceability chain for reported values. A simple check method using conventional statistical means is proposed to detect and to avoid such mistakes related to calibration uncertainties. It is intended to help to ensure a proper uncertainty propagation, to maintain a system of reliable and traceable reference materials. A spreadsheet is provided for the implementation of such a check. Example calculations for published data are presented.