Quality Assurance in Testing Laboratories

General criteria for the operation of testing laboratories according to standards series EN 45000 and quality assurance under ISO series 9000 are discussed, and other quality management systems too are presented. The important elements of quality assurance as concerns measurements, tests and investigations are pointed out. This revised version was published online in August 2006 with corrections to the Cover Date.     

统计质量保证技术在分析测试实验室内部质量控制中的应用

对通过统计质量保证（SQA）技术进行分析测试实验室内部质量控制（IQC）的方法作了初探。研究结果表明,SQA技术的应用能保证实验室始终处于统计受控状态,确保测试数据的有效性,有利于分析测试实验室质量保证活动的开展。     

海洋环境监测实验室间比对试验结果分析评价

分别利用数理统计中Gurbbs检验、F检验和t检验方法对2011年参与东海外海域海洋环境监测的3家实验室比对试验结果进行分析评价.结果表明,3家实验室参与比对项目的数据精密度不尽相同,一些项目的监测结果实验室间存在系统误差.为确保全海域监测数据的一致性,质量保证与控制计划应不断完善.     

标准物质在科研设备质量控制体系中的使用和管理

阐述了标准物质的应用和管理在科研设备质量控制体系中的重要性,指出了现阶段科研设备用标准物质存在的问题,并提出了对策。     

沉积物内多氯联苯测定中有机氯农药的排除及质量控制/质量保证研究

报道了沉积物样品中多氯联苯(PCBs)的分析方法及质量控制/质量保证(QA/QC)研究,结果表明多级复合硅胶柱对有机氯农药去除效果良好.采用25种PCBs同族体标样PCB25对分析方法进行了QA/QC研究,PCBs的平均回收率在97%～118%之间.用本方法测定25种多氯联苯同族体的检测限范围在0.5～1.4ng/g之间.     

A Quality Assurance Study for the Analysis of Hydrocarbons in Sediments

Abstract

Two exercises (MEDCAL I and II) were conducted in our Department during November 1984 and October 1986, with participants from the Mediterranean region, for testing the IOC Manual for the determination of petroleum hydrocarbons in sediments (IOC, Manuals and Guides, No. 11).

The gas chromatographic analysis of the saturated hydrocarbon fraction provided, at the best, a precision of 60% (relative standard deviation RSD) for n-alkanes (mean conc. 0.89 μg/g) and 56 % for the unresolved complex mixture (UCM) (mean conc. 16μg/g). The CPI and the pristane/phytane ratio provided better results (13% RSD). The aromatic fractions, analysed by UV-fluorescence, yielded in total a mean concentration of 10μg/g of chrysene equivalents with a 49% RSD.

The extraction-partition step was confirmed to be the main source of error in the analysis because when the results were corrected for recoveries, the RSD were reduced to 17, 30 and 6% for n-alkanes, UCM and total aromatics, respectively. Our reference intra-laboratory precision was, respectively, 18, 14 and 14%.     

Standardisation and Quality Assurance

Modern DSC instruments generally give very reproducible results that are ideal for quality assurance work. However, various corrections are needed before quantitative data are obtained. Since the corrections differ from one type of instrument to another, it is important to ensure that they are all properly carried out. Without these corrections, it is fruitless to compare data from different sources. The types of problem, and their solutions, are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

土壤中重金属元素检测的质量认证

探讨了土壤中重金属检测能力验证的质量控制措施,为确保能力验证结果的准确性及不断提高实验室的检测技术水平提供参考.     

Harmonisation Of Ec Air Quality Directives

Abstract

The Environment Institute of the Joint Research Centre in Ispra devotes an important part of its activities to support the Commission of the European Communities in scientific and technical matters. As an example of these activities, a general overview is given of the harmonisation work lead by its Central Laboratory of Air Pollution for the implementation of EC air quality directives in the European Member States. The different stages of a directive's development are reviewed and illustrated with typical examples of harmonisation work recently undertaken.

Preparatory actions for future regulations are illustrated by the recent intercomparison exercise for VOC measurements, realized in view of the coming directive on photo-oxidants.

Quality assurance programmes are developed that are mainly focused on the evaluation of sampling, calibration and measurement techniques in the Member States. Special attention is also paid to the harmonisation of network design. The results of a recent network design campaign realised in Madrid, using passive sampling techniques in combination with mobile measurements, are presented.

An example of the development of scientific and technical progress is given by the intercomparison of primary NO₂ calibration standards, where the reference method of the directive was checked and compared to new standard methods.     

湿法程控消解-冷原子吸收方法测定微量汞的质量保证

对使用程序控制温度消解器和原子化发生、测定装置进行程序控制消解温度-湿法消解-氢化物发生-冷原子吸收方法测定微量汞的质量保证进行了研究,提出了人、样品、方法、仪器与器具、环境、试剂六方面的质量保证要点。     

Quality assurance in clinical chemistry laboratories in the UK

 Since the mid-1960s quality assurance in clinical chemistry has progressed from a need to define and improve precision and accuracy in analytical test procedures to an all-embracing process of assuring that the whole process of pre-analytical, analytical and post-analytical phases of handling patient samples is managed effectively and efficiently. Automated and computer-controlled equipment has reduced many of the analytical errors, in particular in imprecision, that were present in manual analysis. New management techniques have been developed to control the quality and appropriateness of results. Developments in internal quality control and external quality assessment procedures have enabled laboratories to continually improve the quality of assays. Laboratory accreditation and external quality assessment scheme accreditation have ensured that peer review and peer pressure have been applied to both laboratory and external quality assessment scheme performance. As the NHS reviews its priorities and places more emphasis on primary care provider demands, hospital laboratories will of necessity assist with near patient testing outside the laboratory. This will provide new challenges to the quality of the service provided. Received: 2 July 1998 · Accepted: 1 August 1998     

Proficiency testing programmes as a tool in food quality assurance: Overview of Italian experiences

Proficiency testing involves the performance of test procedures on routine samples by a number of laboratories. Interlaboratory proficiency testings provide multiple benefits to participants since they play a key-role in the total quality control of laboratory activities. They serve as a means of self-improving, as a mechanism of continuing education and as a source of information for accreditation agencies. This review highlights basic principles, benefits, criteria and capabilities of a proficiency testing programme for food analysis laboratories as well as their role in the implementation of rapidly developing food control legislation.     

Quality assurance and statistical control

In scientific research laboratories it is rarely possible to use quality assurance schemes, developed for large-scale analysis. Instead methods have been developed to control the quality of modest numbers of analytical results by relying on statistical control: Analysis of precision serves to detect analytical errors by comparing thea priori precision of the analytical results with the actual variability observed among replicates or duplicates. The method relies on the chi-square distribution to detect excess variability and is quite sensitive even for 5–10 results. Interference control serves to detect analytical bias by comparing results obtained by two different analytical methods, each relying on a different detection principle and therefore exhibiting different influence from matrix elements; only 5–10 sets of results are required to establish whether a regression line passes through the origo. Calibration control is an essential link in the traceability of results. Only one or two samples of pure solid or aqueous standards with accurately known content need to be analyzed. Verification is carried out by analyzing certified reference materials from BCR, NIST, or others; their limited accuracy of 5–10% make them less suitable for calibration purposes.     

Future trends in analytical quality assurance — the estimation of uncertainty

This paper presents one of the future trends in analytical quality assurance, the evaluation of the quality of analytical results by estimation of their uncertainties. The present state-of-the-art is described, and the impact caused by the declaration of uncertainties in chemical results is foreseen.     

土壤中多环芳烃和酞酸酯类有机污染物气相色谱-质谱测定方法中的质量控制与质量保证

建立了气相色谱-质谱(GC-MS)测定土壤中多环芳烃(PAHs)和酞酸酯类(PAEs)有机污染物的方法。样品经加速溶剂萃取和超声萃取处理后,通过固相萃取或凝胶渗透色谱法进行净化,在选择离子监测模式下进行定量。通过全程序空白、空白加标回收、清洁土壤基质加标回收及有证标准参考物质比对等方式,对所建立的方法进行严格的质量控制和保证。16种PAHs和7种PAEs的方法检出限分别为0.13～2.2 μg/kg和0.19～0.52 μg/kg,平均加标回收率分别为41.5%～116.9%和90.7%~107.1%。本研究所建立的土壤中PAHs和PAEs的GC-MS快速分析方法及其质量控制措施可以为全国性土壤污染状况调查数据的科学性和准确性提供技术保障。     

工业含酚废水的水质分析

采用4－氨基安替比林光度法及荧光法对工业含酚废水进行了检测,并对两种检测结果进行了比较,同时对工业含酚废水水质情况进行了分析,为农田灌溉用水提供了依据。     

Quality assurance system for a decomposition method as demonstrated for the Wickbold combustion technique

 A five-step model for a quality assurance system is developed for an internal quality control check. It includes the quality control of the decomposition method and the detection method as steps belonging together. The Wickbold combustion technique as decomposition method in combination with atomic absorption spectrometry was chosen. The vaporization of the elements mercury, arsenic, lead, antimony and selenium is based on combustion in an oxyhydrogen flame. To check the efficiency of the analytical system, the uncertainty of results was calculated on the basis of the "Guide to the Expression of Uncertainty in Measurement". Received: 13 January 1997 · Accepted: 29 March 1997     

Multivariate standardisation for non-linear calibration range in the chemiluminescence determination of chromium

Multivariate standardisation is proposed for the successful chemiluminescence determination of chromium based on luminol-hydrogen peroxide reaction. In an extended concentration range, non-linear calibration model is needed. The studied instrumental situations were different detection cells, instruments, assemblies, time and their possible combinations. Chemiluminescence kinetic registers have been transferred using piecewise direct standardisation (PDS) method. The optimisation of transfer parameters has been carried out based on the prediction residual error criteria.Non-linear principal component regression (NL-PCR) and non-linear partial least square regression (NL-PLS) were chosen for modelling the relationship signal-concentration of transferred registers.Good accuracy and precision were obtained for water samples. The concentrations of chromium were statistically in agreement with reference method values and with recovery studies. Therefore, it is possible to transfer chemiluminescence curves without loosing ability of prediction, even the presence of a non-linear behaviour.     

Reaction Inhibition as a Method for Preventing Thermal Runaway in Industrial Processes

Summary: In this work inhibitors were used to prevent runaway reactions during methylmethacrylate suspension polymerization processes. The main problem that may more frequently occur in chemical reactors, carrying out free radical polymerization reactions, is the loss of temperature control. The addition of an inhibitor during polymerization processes can be considered as a good method to stop or at the least slow down the reaction. In this work two inhibitors were used: hydroquinone and 1,4-benzoquinone in a series of polymerization experiments. In order to identify situations that can lead to a runaway reaction, an early warning detection system based on the divergence criterion was used. When this system signalled an alarm, small amounts of inhibitor were added to the reaction mixture. The results showed that hydroquinone and 1,4-benzoquinone behave slightly differently and the reactor temperature can be kept within safe limits.     

Improvement of Analytical Measurements within the BCR-Programme: Single and Sequential Extraction Procedures Applied to Soil and Sediment Analysis

Abstract

The determination of extractable trace metal contents in soil and sediment, using respectively single and sequential extraction procedures, is currently performed in many laboratories to assess the bioavailable metal fraction (and related phyto-toxic effects) and the accessability to the environment (e.g. contamination of ground waters).

Owing to the need for validation of the extraction schemes used and of the analytical techniques, the Community Bureau of Reference (BCR) decided to organize a project for the improvement of the quality of determinations of extractable trace metal contents in soil and sediment. The implementation of this project follows a stepwise approach involving feasibility studies, intercomparisons to detect and remove sources of errors in the application of the analytical methods, and the certification of the extractable compounds. This paper describes the organization of the work completed so far (feasibility studies and first intercomparison) and discusses its further development.