Need and use of reference materials in a comprehensive countrywide monitoring of radionuclides

The reliability of measurement results is essential for forming a common database of a laboratory network, because a well-maintained and consistent database is the crucial point of countrywide monitoring. Reference materials are important tools in realizing some aspects of quality assurance; they are especially useful in harmonizing work within the network. Among usual types of reference materials in radio analytics solutions, matrix reference materials and some special reference objects are used. All classes of reference materials should be used depending on the purpose of the demonstration of quality, even in-house reference materials. Interlaboratory measurement comparison and performance evaluation programs play important quality assurance role in radio analytical laboratories. Fortunately, nowadays, the main task is to determine a very low radioactivity concentration in the environment; therefore, pre-concentration is necessary. Generally, the radionuclide bearing natural materials collected from sites where there had been sufficient time for natural processes to redistribute various chemically different species of radionuclides are more reliable reference materials than spiked materials—the main difference is the chemical bounding which is crucial from the point of view of the bioavailability. The need of reference material is summarized according to the intended use, like quality control, measurement validation, and instrument calibration.     

Reference materials for large-scale metal deposition surveys

 In order to ensure quality assurance in large-scale environmental contamination studies involving many different analytical laboratories, the use of calibrated reference materials is essential. Prior to a survey of atmospheric metal deposition in 1995 comprising 20 countries and covering large parts of Europe, the lack of suitable reference materials of moss and organic-rich soil was apparent. In order to improve the quality of analytical data to be produced in this international survey, candidate analytical laboratories were invited to participate in an intercomparison exercise. Three moss and three soil humus reference samples specifically prepared for this purpose were distributed anonymously among the laboratories, which were asked to report data for ten priority elements (V, Cr, Fe, Ni, Cu, Zn, As, Cd, Hg, Pb) and as many additional elements as they determined normally. In this paper the analytical data from the intercomparison are evaluated, and recommended values for the ten priority elements and 17 additional elements (B, Na, Mg, Al, S, K, Ca, Mn, Co, Se, Rb, Sr, Sb, Cs, Ba, La, Th) in each of the six reference samples are established. These samples should be useful for similar future studies including areas where the contamination levels are very low. Received: 17 October 1996 Accepted: 2 January 1997     

From misconception to a must: The measured merits of total quality management and accreditation in INAA

Increasingly govemmental bodies and industry require that supporting analytical laboratories have their quality assurance program implemented in a quality system by international standards such as derived from the ISO-25 guide. Neutron activation analysis (NAA) laboratories may have to deal with this trend too. In universities and research laboratories the need for it, and the implications of total quality management system are sometimes misconceived by unfamiliarity with the issue. The laboratory for INAA in Delft has been accredited for its quality system since 1993. Some of the tangible improvements since the introduction of quality management are presented. Four strategical considerations are given to consider the introduction of quality management at NAA laboratories, viz. with respect to the role of NAA for the validation of other methods, the role of NAA in the certification of reference materials, the preservation of knowledge and the acceptance of NAA as a respectable method.     

Reliability of food measurements – a South African perspective

 High quality analysis of food involves a comprehensive process, which includes proper sampling, validated methodology, experienced technical staff and the use of standard reference materials. Today there is more international emphasis not only on generating food composition data but also on data quality and the main issue is that South African data should be internationally recognized as acceptable and representative. Quality is multi-dimensional and should at least include aspects of accuracy, precision and representativeness. A major step forward is that laboratories can apply for accreditation, which involves, inter alia, documented, validated methodology, regular interlaboratory studies, the use of certified reference materials and the existence of a sound quality system. The South African National Accreditation System (SANAS) is a regulatory body in South Africa, which is internationally recognized. Assessment of laboratories against specific standards is performed regularly and laboratories have to comply with certain managerial and technical requirements. Once a laboratory is accredited, ongoing validation and verification of results as well as regular assessment ensure reliability of results and overall competency of the laboratory. With a quality assurance programme in place, the reliability of results of the Irene laboratory is beyond doubt and nutrient data could be included in food composition tables. Received: 31 January 2002 Accepted: 4 February 2002 Correspondence to Louwrens Erasmus Smit     

Quality assurance in the microbiology laboratory

 The pertinent issues necessary for the establishment of quality assurance in the microbiology laboratory are discussed. Quality assurance is a planned system of control measures that enables management to ensure that the analytical data produced in the laboratory are valid. To introduce quality assurance, all activities in the laboratory that affect the production of analytical data must be documented and controlled. These include sampling, method selection, laboratory environment, equipment, reagents and media, staff, reference materials and internal and external quality control. Laboratory accrediation in accordance with EN45001 and ISO Guide 25 enables laboratories demonstrate to an external agency their ability to perform analytical work and produce valid analytical data. This gives creditability to the laboratory and allows management to have confidence in the data produced. Received: 6 June 1995 Accepted: 3 July 1995     

Biological reference materials in routine analysis: Results from the German Food Contamination Monitoring Programme

Summary Within the research project German Food Contamination Monitoring Programme, selected foodstuffs have to be examined by the official food control laboratories. Contents of pesticides and heavy metals have to be determined by means of routine analysis. Biological reference materials are used in collaborative studies and in parallel investigations for analytical quality assurance. Using lead as an example, results obtained for three reference materials are discussed.     

The BIOREMA project—part 1: Towards international comparability for biofuel analysis

There is an increasing demand to accurately measure the quality of biofuel products (e.g. biodiesel and bio-ethanol). This demand is driven in Europe by directives promoting the use of renewable sources of energy and worldwide by national and international legislation setting out quality requirements for these fuels. Until now, there has been no international consensus on the minimum technical specifications to ensure biofuel quality. Furthermore, it is unclear which reference materials and measurement techniques are needed to provide the quality assurance and quality control framework to underpin these legislative requirements. As part of the European Commission’s 7th Framework Programme, the BIOREMA project (REference MAterials for BIOfuel specifications) demonstrated the feasibility of preparing biodiesel and bio-ethanol reference materials with reference values traceable to the international system of units for a range of parameters at levels relevant to technical specifications. However, the project concluded also that further research is needed to improve the current measurement capabilities for some parameters. Within the BIOREMA project, two global interlaboratory comparisons were carried out, using the biodiesel and bio-ethanol test materials prepared during the feasibility stage of the project, as well as two biodiesel standard reference materials from the National Institute of Standards and Technology (NIST, USA). The exercises showed that the measurement capabilities of the field laboratories were in many cases satisfactory, whereas for other laboratories the availability and regular use of certified reference materials would likely enhance the measurement capabilities for many of the parameters studied. A general overview of the BIOREMA project is presented in this paper. The details of the production of the two types of BIOREMA reference materials, and the results of the interlaboratory comparison for the bio-ethanol and biodiesel study materials, are discussed in parts 2 and 3 of this series of papers.     

Quality assurance in analytical laboratories engaged in research and development activities

 Research and development activities are carried out by various types of laboratories that are not the typical testing and calibration laboratories for which the ISO/IEC 17025 is the quality assurance implementation reference. In this paper, such laboratories engaged in R&D activities are classified and different approaches they can adopt with a view to implementing a quality system that are suited to their characteristics and the type of work they conduct are proposed. These approaches take account of existing standards for the certification/accreditation of laboratories and of guides on quality assurance for non-routine analytical laboratories. Received: 11 July 2002 Accepted: 29 November 2002 Presented at Analytica Conference, 23–26 April 2002, Munich, Germany Correspondence to M. Valcárcel     

Preparation of a reference material “Creatinine in Human Urine”

Two batches of a reference material “Creatinine in Human Urine” have been prepared with creatinine concentrations at the physiological level, and used in interlaboratory comparisons in which up to 26 laboratories participated employing up to 4 independent methods. The 95% confidence intervals obtained for the certified creatinine concentrations are better than the “acceptable ranges” of commercially control samples available for clinical laboratories, the certified values being traceable to mean values of the commercial control samples. Thus, a suitable reference material has been prepared for the quality assurance of environmental and occupational health studies in which the concentration of a pollutant or its metabolites in human urine has to be related to the creatinine concentration.     

Toward standardization of quality assessment in laboratory medicine by using the same matrix samples for both internal and external quality assessments

The main purpose of quality assurance procedures in clinical laboratories is to ensure that test results are appropriate to maintain excellence in the diagnosis, monitoring, and treatment of disease. However, in current practice, no standardized procedure or frequency for the evaluation of methods exists, particularly in external quality assessment. Furthermore, different quality control materials are typically used for internal and external quality assessment. To overcome these discrepancies, we used samples with the same matrix for both internal and external quality assessments of a group test performed in our laboratory. We then calculated total error using real bias (target value obtained by reference method) and the imprecision of each test and compared our results with the total error allowable, derived from biological variation data. We suggest that the strategy of using the same matrix samples for both internal and external quality assessment is cost-effective, can be readily used by staff, and will facilitate the standardization of quality control in clinical laboratories.     

The role of reference materials in food analysis

Reliability and accuracy of measurements in food and agricultural materials are essential both for implementation of the legislation concerning public health and consumer protection and for the elimination of disputes arising from trade requirements and technical barriers. In such process the crucial step is represented by the programmes aimed at the quality assurance of analytical data produced by laboratories involved in food analysis. In this framework a major role is played by the proper use of reference materials. This report provides an overview on relevance, availability, use, certification procedures and perspective of reference materials in food analysis. Measurement harmonization procedures are also discussed.     

The handbook of analytical methods for trace elements as adopted by the national reference laboratories for residues

The instrumental approaches, quality assurance schemes and management of chemical laboratories should in general be harmonized at the highest possible level. This is all the more so for the national reference laboratories (NRLs) for residues in live animals and their products which have to implement quality assurance systems inspired to the principles of good laboratory practice as well as to the general norms for the operation of testing laboratories (EN 45000 criteria). Directive 23/96/EC of 29 April 1996 prescribes that NRLs are assisted in this process by the four community reference laboratories (CRLs) for residues. To this end, the Rome CRL systematically collects in a handbook all the analytical methods in use at NRLs for the determination of As, Cd, Cu, Hg and Pb, as well as other chemical elements, in animal matrices. One major goal of this action is to foster the harmonization of analytical approaches by the NRLs and their ability to provide comparable results of similar quality. The Rome CRL is committed to revise this handbook twice a year. The role of the handbook is also to encourage the exchange of information among the NRLs as regards the possibility of improving existing methods.     

Analytical validation of quality control materials for Huntington’s disease examination

The expansion of molecular diagnostics using nucleic acid technologies in clinical and public health practice has increased the need for appropriate reference materials and verified quality-control materials for quality assurance, test validation, proficiency testing and the development of new examination procedures. Good laboratory practice requires the use of reference materials to establish an examination procedure and assess the variability of the results. Reference materials are also required to assess the assay on a daily basis and to normalize results collected among different laboratories. Despite the growing volume, the rapidly increasing number of tests being offered, and the necessary routine use, certified reference materials are often not available. There is a wide range of human genetic bio-assays for which there are no available traceable certified reference materials. Several initiatives have been organized to provide well-characterized quality control specimens (e.g., cell lines) with known DNA mutations for use in diagnostics. Mutations are confirmed with bi-directional DNA sequence analysis, which is considered the reference examination procedure. In the field of personalized medicine, NIST has created and validated Standard Reference Material^® 2399 for fragile X examinations. Herein we describe our characterization of candidate reference materials for Huntington’s disease genetic examination. Bi-directional DNA sequencing confirmed the size of the CAG repeat contained on each allele from patient derived materials. Amplification and capillary electrophoresis of the CAG repeats had an uncertainty ranging from 2.06%CV to 7.83%CV.     

Quality assurance in environmental research: emissions and fate of platinum

Summary Quality assurance in environmental research is related to reliable analytical methods. According to this fact great efforts were taken in the German Cooperative Project sponsored by the Ministry of Research and Technology Emissions of Precious Metals to ensure the quality of all analytical data from various research groups. As there are only few certified reference materials (CRMs) for platinum available and the application of reference materials is an important measure in quality assurance and quality control actions in every laboratory, several materials have been prepared with low and elevated platinum contents as reference samples for this project. These reference samples were a catalyst sample with elevated platinum content, a dust reference material with low platinum content and a catalyst reference material with low platinum content. With these reference samples and the Canadian geological reference material SU-1a interlaboratory studies were conducted and the results of these are presented in this paper.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Quality and comparability of measurement of potentially toxic elements in urban soils by a group of European laboratories

A study has been conducted to assess the quality and comparability of measurement of aqua-regia-soluble cadmium, chromium, copper, iron, manganese, nickel, lead, and zinc in urban soils within a small cohort of European research laboratories specializing in soil science or environmental analytical chemistry. An initial survey indicated that highly variable levels of analytical quality control (e.g. use of certified reference materials) were routinely implemented in participant laboratories. When a set of soil samples—differing in metal contents and in characteristics such as pH and organic-matter content—were exchanged and analysed, approximately 20% of results differed from target values by more than 25%. A principal-component analysis was applied to data for chromium, copper, nickel, lead, and zinc, and proved successful in assessing overall laboratory performance. The study indicates that greater prominence needs to be given to quality assurance and control if comparable data are to be generated in international, collaborative research projects.     

IAEA reference materials for quality assurance of marine radioactivity measurements

The IAEA's Marine Environment Laboratory has been assisting laboratories in Analytical Quality Control Services (AQCS) for the analysis of radionuclides in the marine environment since the early seventies. AQCS through world-wide and regional intercomparison exercises and the provision of reference methods and reference materials (RM) have been recognized as an important component of quality assurance/quality control. A total of 43 intercomparison exercises were organized and 37 RM were produced for marine radioactivity studies. All important marine matrices were covered, e.g., seawater, marine sediments of different chemical compositions, fish, shellfish and seaplants. RM were prepared from samples collected at contaminated sites (e.g., the Irish Sea, the Baltic Sea, the Arabian Sea, Mururoa and Bikini Atolls, etc.) as well as from sites affected only by global fallout (e.g., the Pacific Ocean). Available RM are listed in the IAEA biennial catalogue and can be purchased at a minimal price. An overview of prepared RM for radionuclides in marine matrices is presented and discussed in more detail.     

Metrological concept for comparable measurement results under the European water framework directive: demonstration of its applicability in elemental analysis

Within the scope of a project of the “European Association of National Metrology Institutes??(EURAMET), a European metrological dissemination system (network) providing traceable reference values assigned to matrix materials for validation purposes is described and put to the test. It enables testing laboratories (TL) to obtain comparable results for measurements under the “EU Water Framework Directive 2000/60/EC??(WFD) and thus, to comply with a core requirement of this very directive. The dissemination system is characterized by the fact that it is available to all laboratories throughout Europe which intend to perform measurements in the context of the WFD and that it can ensure sustainable metrological traceability to the International System of Units (SI) as a reference point for the measurement results. This dissemination system is set up in a hierarchical manner and links up the level of the national metrology institutes (NMI) with that of the TLs via an intermediate level of calibration laboratories (CL) by comparison measurements. The CLs are expert laboratories with respect to the measurement of the analytes considered here (within the project, the CLs are called potential calibration laboratories (PCL)) and are additionally involved in the organization of comparison measurements within the scope of regional quality assurance (QA) systems. Three comparison measurements have been performed to support the approach. A total of about 130 laboratories participated in this exercise with the focus on the measurement of the priority substances Pb, Cd, Hg, and Ni defined in the WFD. The elemental concentrations in the water samples roughly corresponded to one of the established environmental quality standards (EQS), the annual average concentration (AA-EQS), which is defined in the daughter Directive 2008/105/EC of the WFD. It turned out that a significant number of TLs still need to improve their measurement methods in order to be able to fulfill the minimum requirements of the WFD, in particular, with regard to the elements Cd and Hg probably due to their low EQS values. Furthermore, it became obvious that the hierarchical dissemination system suggested here actually corresponds to the measuring capabilities of the three participating groups (NMIs, PCLs, and TLs).     

NIST reference materials to support accuracy in drug testing

Substance abuse is a major problem worldwide. There is considerable emphasis placed upon testing individuals for evidence of use of controlled substances. Because the consequences of a positive test can be quite severe, laboratories conducting such tests must rigorously follow a carefully designed quality assurance program. Such a QA program should include use of reference materials to assure that the methods used to detect and quantify drugs are providing accurate results. The National Institute of Standards and Technology (NIST) supports accuracy in drugs of abuse testing by providing Standard Reference Materials (SRMs) with certified concentrations of drugs of abuse in urine- and hair-based reference materials. NIST, working in collaboration with the College of American Pathologists (CAP), has developed urine-based SRMs for marijuana metabolite, cocaine metabolite, morphine and codeine, and morphine glucuronide and CAP Reference Materials for amphetamines and phencyclidine. Certification measurements performed at NIST involve two independent methods for each analyte, one of which always uses GC/MS with the other usually being an LC method with either MS or UV detection. Work has recently been completed on a seven component drug in urine SRM. In addition NIST conducts research in the analysis of hair for drugs of abuse. To assist laboratories testing hair for that purpose, NIST has developed two drugs in hair reference materials.College of American Pathologists Research Associate at NIST     

Development of reference materials for the analysis of acid-extractable metals in sludge

The development of reference materials to verify the determination of metals in sludge is described. Effluents from domestic and industrial treatment facilities were dried, size-reduced and homogenized. Multiple aliquots of each material were analyzed in two different government laboratories to determine reference values for the acid-extractable concentrations of more than 15 metals. These acid-extractable concentrations are distinct from total metal values. Different sample preparation and instrumental methods, along with internal quality assurance protocols, were used to confirm the results. The data show good agreement for most metals in the domestic material. Reference values for the leachable concentrations of several toxic metals and major constituents will become part of the Certificate of Analysis for Standard Reference Material (SRM) 2781 issued by the National Institute of Standards and Technology (NIST). Data for the candidate industrial sludge reference material are also presented and discussed.