The development of gas standards and calibration techniques for measurements of vehicle, aircraft and industrial emissions, natural gas, occupational exposure and air quality

 The National Physical Laboratory (NPL) is involved in the dissemination of nationally traceable standards to which measurements of air quality, occupational exposure and air pollution source emissions, and natural gas analyses, can be referenced. This has required the development of national primary gas standards using absolute gravimetric and other techniques, and the development of dynamic calibration techniques for gaseous species which would be unstable in high-pressure cylinders. The methodology used for preparing gas standards gravimetrically is described, together with the rigorous quality assurance measurements and consistency checks which are used to demonstrate their accuracy and stability. The uncertainty budget assigned to these standards will also be summarised. NPL primary standards are used to certify traceable 'secondary' gas standards which are disseminated so as to ensure the accuracy of gas analysis measurements. Examples of the applications of these secondary standards are presented. The gas standards are employed in proficiency testing of industrial stack-testing organisations, and results of the initial rounds are presented. NPL gas standards are also now being used as the basis of the United Kingdom Environment Agency's new type-approval and certification scheme for continuous industrial stack-emission analysers. A recent important international initiative, in the field of gas analyses, is the agreement by national standards laboratories across the world to demonstrate the equivalence of their calibrations, by means of key comparisons between them. These worldwide key comparisons are complemented in Europe through the EUROMET initiative which seeks to establish the equivalence and comparability of calibration standards held at national standards laboratories across Europe. Examples of these intercomparisons are presented. Received: 23 March 2000 / Accepted: 18 August 2000     

Integration of metrological principles in a proficiency-testing scheme in the field of water analysis

Measurement traceability is universally recognised as one of the basic prerequisites for comparability of results obtained in different laboratories and is a basic aspect of metrological sciences such as analytical chemistry. This requirement is underscored by the increasing adoption of standards and measurement quality systems, such as laboratory accreditation against ISO/IEC 17025. Testing laboratories ensure traceability of their measurement results by using appropriate reference standards for calibration of instruments and control of measurement processes. For routine work in the field of water analysis, these standards are usually commercial solutions or in-house solutions prepared from pure products. Therefore, laboratories should demonstrate that their use of reference standards is appropriate and sufficient, which can be done by participation in an appropriate proficiency-testing scheme. The paper reports how measurement traceability of results from field laboratories (nitrite nitrogen, nitrate nitrogen, chloride and sulphate; all in water) can be demonstrated by participation in a proficiency-testing scheme based on reference values.     

水中易释放氰化物能力验证样品的研制及应用

根据国家地表水环境质量监测网监测任务要求和环境监测的实际需要,制备了水中易释放氰化物能力验证样品。通过均匀性、稳定性检验以及量值一致性评价,研制的样品均匀性良好,在3℃~6℃冷藏避光保存条件下1年内稳定,样品配制值与多家实验室协作测定结果一致。探讨了样品在能力验证活动中的应用,共有来自全国11个省的32家实验室参加了水中易释放氰化物的能力验证计划,实验室满意率在80%以上,实验室结果出现有问题或不满意主要是由于样品前处理以及检测过程质量控制不当导致的。经检测及实验室反馈的数据验证,该能力验证样品能够应用于能力验证活动。     

Quality (r)evolution – guidelines and practical implementation of quality management: the U.S. perspective

 All clinical laboratories in the United States were required for the first time in 1992 to comply with universal minimum regulations: the Clinical Laboratory Improvement Amendments of 1988 (CLIA'88). The CLIA'88 regulations precipitated revolutionary and evolutionary changes based in both total quality management and continuous quality improvement principles. The regulations specify minimum requirements for personnel, quality control, and proficiency testing. Under quality assurance, the requirements are more individualized and allow laboratories to meet the needs of their customers while being in compliance with the regulations. Biannual inspection is integral to CLIA'88. However, laboratories can choose other federally approved, "deemed" professional organizations, with regulations equivalent to CLIA'88. Selection of one of these organizations allows for some flexibility in the application of the requirements, and eliminates having federal CLIA'88 inspectors perform the inspection. Since CLIA's inception in 1992, inspectors have noted a decline in the number of deficiencies cited. An improved level of proficiency testing performance also indicates that better quality test results are being provided to clinicians. The quality evolution and revolution will continue in the United States, and a major impetus will be health care reform's mandate to reduce cost. Received: 13 December 1995 Accepted: January 1996     

Quality and timeliness in medical laboratory testing

In terms of testing, modern laboratory medicine can be divided into centralized testing in central laboratories and point-of-care testing (POCT). Centralized laboratory medicine offers high-quality results, as guaranteed by the use of quality management programs and the excellence of the staff. POCT is performed by clinical staff, and so such testing has moved back closer to the patient. POCT has the advantage of shortening the turnaround time, which potentially benefits the patient. However, the clinical laboratory testing expertise of clinical staff is limited. Consequently, when deciding which components of laboratory testing must be conducted in central laboratories and which components as POCT (in relation to quality and timeliness), it will be medical necessity, medical utility, technological capabilities and costs that will have to be ascertained. Provided adequate quality can be guaranteed, POCT is preferable, considering its timeliness, when testing vital parameters. It is also preferred when the central laboratory cannot guarantee the delivery of results of short turn-around-time (STAT) markers within 60 or (even better) 30 min. POCT should not replace centralized medical laboratory testing in general, but it should be used in cases where positive effects on patient care have been clearly demonstrated.     

The American (USA) perspective six years after implementation of CLIA'88 (Federal) regulations

 On September 1, 1992 all testing sites in the United States were required to comply with the Clinical Laboratory Improvement Amendments of 1988 (CLIA'88). These regulations, based on both total quality management (TQM) and continuous quality improvement (CQI) principles, reshaped the environment for more than 90% of laboratories. CLIA'88 represented a revolutionary change by imposing universal, uniform regulations based on test complexity for all sites examining materials derived from the human body for the purpose of providing information for the diagnosis, prevention, or treatment of disease. CLIA'88 specifies minimum requirements for personnel, quality control, and proficiency testing (PT). In addition, laboratories are required to follow manufacturers' directions and comply with other specified good laboratory practices. PT is mandated for most of the frequently run analyses and quality assurance requirements integrate the principles of CQI as well as TQM into the regulatory process. Biannual inspection is integral to CLIA'88, however, laboratories can choose other federally approved ("deemed") professional organizations, such as the Commission on Office Laboratory Accreditation, the College of American Pathologists, or the Joint Commission on Accreditation of Healthcare Organization, having standards that meet or exceed those of CLIA'88. CLIA'88 has still not been finalized. This article discusses the impact and changes since CLIA's implementation in 1992. Received: 5 October 1998 · Accepted: 20 October 1998     

The increasing demands of quality assurance in chemical testing

The chemical and microbiological testing community is going through a rather difficult period of change. Publication of ISO/IEC 17025 (General requirements for the competence of Calibration and Testing Laboratories, 1999) [1] is placing additional demands on testing laboratories to ensure traceability and estimate uncertainty in their measurements. At the same time, laboratories must remain mindful of the need to provide relevant, timely and economic services to their clients. International Accreditation New Zealand (IANZ) and its accredited laboratories are currently focussing on establishing realistic methods for ensuring traceability to national and international standards and estimating measurement uncertainty. To this end, IANZ recognizes that it has an important role in providing as much advice and assistance as possible, not only to its accredited chemical laboratories but also to all those contemplating accreditation in New Zealand.

Evaluation of analyte stability and method ruggedness in the determination of streptomycin residues in honey by liquid chromatography with post-column derivatization

This study demonstrated that streptomycin in honey is quite stable, and the results showed no obvious differences for 3 samples containing incurred analyte during continuous testing for 4 months. Fifteen laboratories evaluated method performance at 4 fortification levels ranging from 0.010 to 0.100 mg/kg; the recoveries ranged from 73.7 to 78.5%, the reproducibility relative standard deviations ranged from 5.76 to 15.85%, and the repeatability relative standard deviations ranged from 1.64 to 3.80%. In 1999-2002, the method was used to determine streptomycin residues in 5106 lots of honey samples from >20 provinces all over China. All of the honey samples were found to be in conformity with the requirements of customs clearance for exports to Europe, the United States, and Japan. The continuous 4-year quality analysis also found that C18 solid-phase extraction cartridges should be standardized to ensure that the analytical results are accurate when different lots of cartridges are used.     

Quality assurance in research laboratories

During the last decade, it has become increasingly important that researchers demonstrate that research is conducted to the highest standards. The implementation of quality assurance for research laboratories will enable all fields of research and development to be judged impartially. There are no specific standards for research laboratories but where possible, existing standards can be adapted. This review is structured around two approaches. The first considers research to be a logical extension of testing, and it is assumed that testing standards can be applied methodically to each step in a research project. The second advocates a flexible approach, with research-specific criteria for assessing quality. The important papers published on this topic have been reviewed. The conclusions are that the general quality management approach, encompassed by the ISO 9000 series of standards with the emphasis on customer satisfaction and ‘fitness for purpose’, is suitable for implementing quality assurance in research laboratories.     

Reproducibility of Mooney viscosity measurements made at different laboratories—A discussion of the problem

A cross-check with 12 participants has shown considerable differences between Mooney viscosity readings of different laboratories on four polymers. The mean difference for the identically prepared polymers was 7·7 MU (Mooney units) and the differences for individual polymers up to 11 MU. When the samples were prepared by the individual participants the differences were 7·4 MU for this viscosity range. The author attributes these differences partly to non-compliance with the standards as to the instruments and sample preparation and partly to vagueness of the standards themselves.Although definite amendments to the standards can be suggested, improvement of the instruments cannot be achieved at short notice. The differences between the measurements of different laboratories should therefore be ascertained through routine testing of standard samples; they could then be taken into account in the polymer delivery specifications.     

Laboratory accreditation: The operation of an established scheme

NAMAS, the National Measurement Accreditation Service, was formed in 1985 and has currently accredited some 1050 testing and calibration laboratories in the United Kingdom. NAMAS is managed by an Executive of 60 staff which is based at the National Physical Laboratory, one the UK's largest Government Research Establishments. Laboratories seeking accreditation are assessed by fully trained technical experts contracted by NAMAS, against the criteria set out in the NAMAS Accreditation Standard M10; the criteria contained in this document are fully consistent with the international standards for laboratory accreditation EN 45001 and ISO Guide 25. NAMAS has recently published a document which provides guidance on the interpretation of the NAMAS Accreditation Standard for analytical laboratories. Assessment involves a consultative preassessment visit which is followed by a thorough on-site assessment of a laboratory's quality system and testing activities by a team of expert assessors. Following the correction of any noncompliances found at the assessment, the laboratory receives a certificate of accreditation and a schedule which defines those tests and analyses for which the laboratory is accredited. NAMAS has negotiated a number of mutual recognition agreements with similar accreditation bodies in other countries and negotiations with other schemes are underway. The imminent approach of the European Single Market has highlighted the need for independent third party assurance of testing and calibration and this should ensure the continued growth of NAMAS and similar schemes elsewhere in Europe.     

Practical uses of proficiency testing as valuable tools for validation and performance assessment in environmental analysis

Besides their role as an external quality control tool, PT results or samples could be used as an alternative to fulfil some of the quality assurance requirements such as analytical precision, uncertainty assessment, and internal quality control. This additional use of proficiency testing could help laboratories to reduce the financial impact of their quality assurance process. The purpose of this paper is to highlight some practical uses of PT results or samples in the environmental analytical field, which have been implemented at ISSeP (Institut Scientifique de Service Public), either for method validation or for internal quality control.Presented at the Eurachem PT Workshop September 2005, Portorož, Slovenia     

QUASIMEME results of laboratories involved in the German Marine Monitoring Programme for the North and Baltic Seas

This case study is written for laboratories in the German Marine Monitoring Program (GMMP) for the North and Baltic Seas in order to give support to the assessment of proficiency testing results for their external quality assurance. A second issue is to provide a practical, understandable and common way for the calculation of laboratory performance parameters, so-called combination scores. In this paper, the GMMP laboratory proficiency testing results of QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe) Laboratory Performance Studies for the last 5 years were reviewed. Combination scores for organochlorine pesticides and chlorinated biphenyls in marine sediment are presented and explained. However, the assessment approach is very general and should be applicable to most testing laboratories in the chemical field.Presented at the Eurachem PT Workshop September 2005, Portorož, Slovenia     

Interlaboratory comparison of actinides in human tissue239Pu and240Pu

An international laboratory intercomparison of actinides in human tissues was organized by the United States Transuranium Registry and the National Institute of Standards and Technology. Five laboratories from the United States, United Kingdom, and Japan participated in the intercomparison. The laboratories were requested to analyze Standard Reference Materials 4351 (Human Lung) and 4352 (Human Liver) for²³⁹Pu and²⁴⁰Pu concentration. Approximately equivalent measurement capabilities were generally found among the participants. The results of this intercomparison were statistically comparable to those used for the original certification of the SRM's and were combined for a re-evaluation of the certified values. The combined data sets provide a better characterization of the inhomogeneity of these reference materials and result in a better basis for certification.Deceased.     

Comparability and compatibility of proficiency testing results in schemes with a limited number of participants

Comparability and compatibility of proficiency testing (PT) results are discussed for schemes with a limited number of participants (less than 20–30) based on the use of reference materials (RMs) as test items. Since PT results are a kind of measurement/analysis/test result, their comparability is a property conditioned by traceability to measurement standards applied in the measurement process. At the same time, metrological traceability of the certified value of the RM (sent to PT participants as test items) is also important, since the PT results are compared with the RM certified value. The RM position in the calibration hierarchy of measurement standards sets the degree of comparability for PT results, which can be assessed in the scheme. However, this assessment is influenced by commutability (adequacy or match) of the matrix RM used for PT and routine samples. Compatibility of PT results is a characteristic of the collective (group) performance of the laboratories participating in PT that can be expressed as closeness of the distribution of the PT results to the distribution of the RM data. Achieving quality-of-measurement/analysis/test results in the framework of the concept “tested once, accepted everywhere” requires both comparability and compatibility of the test results.     

Uncertainty evaluation in proficiency testing: state-of-the-art, challenges, and perspectives

The evaluation of measurement uncertainty, and that of uncertainty statements of participating laboratories will be a challenge to be met in the coming years. The publication of ISO 17025 has led to the situation that testing laboratories should, to a certain extent, meet the same requirements regarding measurement uncertainty and traceability. As a consequence, proficiency test organizers should deal with the issues measurement uncertainty and traceability as well. Two common statistical models used in proficiency testing are revisited to explore the options to include the evaluation of the measurement uncertainty of the PTRV (proficiency test reference value). Furthermore, the use of this PTRV and its uncertainty estimate for assessing the uncertainty statements of the participants for the two models will be discussed. It is concluded that in analogy to Key Comparisons it is feasible to implement proficiency tests in such a way, that the new requirements can be met. Received: 29 September 2000 Accepted: 3 December 2000     

Environmental analysis in the Czech Republic: organisation of proficiency testing and its use in laboratory assessment

The history, origin, and development of a system for monitoring and assessing water and other environmental laboratories in the Czech Republic is described. The system started in 1991 and has matured to its present complexity with similarities to the accreditation systems found in other countries. Differences from internationally recognized procedures are being corrected step by step. During the first year of its existence ASLAB, as part of its brief, organised proficiency testing (PT) programs for fifty laboratories. Today the total number of regularly participating laboratories exceeds 700 from the Czech Republic, the Slovak Republic, and Germany. This paper describes the ASLAB PT system, discusses some experiences with its use, and describes the use of PT results in assessment of the competence of laboratories. Received: 12 October 2000 Accepted: 7 January 2001     

Quality issues in proficiency testing

 Proficiency testing is a means of assessing the ability of laboratories to competently perform specific tests and/or measurements. It supplements a laboratory's own internal quality control procedure by providing an additional external audit of their testing capability and provides laboratories with a sound basis for continuous improvement. It is also a means towards achieving comparability of measurement between laboratories. Participation is one of the few ways in which a laboratory can compare its performance with that of other laboratories. Good performance in proficiency testing schemes provides independent evidence and hence reassurance to the laboratory and its clients that its procedures, test methods and other laboratory operations are under control. For test results to have any credibility, they must be traceable to a standard of measurement, preferably in terms of SI units, and must be accompanied by a statement of uncertainty. Analytical chemists are coming to realise that this is just as true in their field as it is for physical measurements, and applies equally to proficiency testing results and laboratory test reports. Recent approaches toward ensuring the quality and comparability of proficiency testing schemes and the means of evaluating proficiency test results are described. These have led to the drafting of guidelines and subsequently to the development of international requirements for the competence of scheme providers. Received: 2 January 1999 · Accepted: 7 April 1999     

Review of European Union requirements: quality standards for food analysis laboratories

 The European Union has prescribed strict quality standards for official food laboratories and the methods of analysis to be used in laboratories when carrying out official food control work. These requirements, which are based on accreditation, participation in proficiency testing schemes and using validated methods of analysis, are described in detail. The similar approach being taken within the Codex Alimentarius Commission is also outlined. The procedures prescribed will ensure that official food control laboratories have in place the measures to ensure that consistently reliable data can be produced. Received: 29 November 1995 Accepted: 8 January 1996     

The estimation and use of measurement uncertainty for a drug substance test procedure validated according to USP <1225>

The vision for metrology at the United States Pharmacopeia (USP) is for international recognition, harmonization, and official acceptance of all USP reference standards that are based on sound, scientific, metrological principles, such as measurement uncertainty (MU). Pharmaceutical testing laboratories will need to estimate the MU for their test procedures. This paper demonstrates how to estimate MU for a test procedure validated following the requirements in USP General Chapter <1225>, Validation of Compendial Procedures. The test procedure determines the assay and impurities for a pharmaceutical drug substance. Pharmaceutical manufacturing companies are required to test the drug substance used in their drug products. In this example, a new test procedure was developed and validated following the requirements in USP <1225>. The MU was estimated using the data from the test procedure validation. The MU estimate determined that the test procedure was fit for use with one determination, avoiding the expense of duplicate determinations. The MU estimate was used to set up decision rules for comparing test data to the assay and impurity specifications. The information from the MU estimate was used to monitor the routine use of the test procedure using control charts that assess accuracy and precision of each run based upon actual test procedure performance capability.