Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.9, #4-5)
The ninth international symposium on biological and environmental reference materials (BERM-9), Berlin, Germany, June 15–19, 2003
by J. Pauwels; H. Emons; S. Wise (pp. 189-190).
Standardization of BSE rapid test performances and experiences gathered during the implementation of large-scale testing by Anne Buschmann; Ute Ziegler; Martin H. Groschup (pp. 191-197).
The accumulation of pathological prion protein is used as a diagnostic marker for transmissible spongiform encephalopathies. According to European Union (EU) regulations cattle older than 30 months of age (Germany, France, Italy, and Spain by national law >24 months) and slaughtered for human consumption must be tested by using rapid tests for bovine spongiform encephalopathy (BSE). Likewise fallen stock and clinically affected animals must be tested. This article gives a short overview of the incidence of BSE in Europe. The diagnostic hierarchy, i.e., the officially approved methodology for the confirmation of suspect rapid test cases, and the organization of the numerous laboratories involved in this large-scale testing for BSE are described. Special emphasis is given to necessary quality control measures currently in place for BSE rapid testing laboratories and to measures intended to assure a consistent performance of the commercially available rapid test kits.
Keywords: Bovine spongiform encephalopathy; Rapid tesing; Standardization; Reference material; Proficiency testing; Quality assurance
Improvements in efficiency of production and traceability for certification of reference materials by Gill Holcombe; Richard Lawn; Mike Sargent (pp. 198-204).
Issues of current interest to certified reference material producers are addressed. Alternative strategies for certification of matrix reference materials are discussed and the benefits of adopting a flexible, cost-effective approach are described. The difficulty of undertaking homogeneity testing where certification is to be carried out with definitive techniques capable of providing very small measurement uncertainty is discussed. Methodology is described which combines conventional screening of the candidate material for homogeneity with an additional, precise assessment of homogeneity based on isotope dilution mass spectrometry measurements. A systematic procedure for evaluating the commutability (horizontal traceability or scope) of matrix reference materials has been evaluated and shows that in some circumstances matrix effects may be less pervasive than is generally believed. This offers the possibility, especially for trace analysis applications, of more efficient use of existing reference materials without compromising measurement reliability. Vertical traceability of matrix reference material data is of growing interest but is difficult to achieve with present interlaboratory certification exercises. A modification is described which attempts to address this issue. It also offers the possibility of improved identification of outliers and reduced variation of data between the participating laboratories.
Keywords: Matrix reference material; Traceable; Commutability; Homogeneity; Certification
Reference materials for checking the performance of qualitative tests (presence/absence of pathogenic micro-organisms): properties, future needs, use in method validation by Hermann Glaeser (pp. 205-208).
Foodstuffs shall not contain pathogenic micro-organisms in concentrations which may cause a risk for consumer health. The relevant legislation therefore normally contains the requirement that these organisms are “absent” in a certain product quantity (e.g. 25 g). It is not at all easy to prove the “absence”. Reference materials are important tools for checking the performance of qualitative methods. These materials should contain the target organism in low numbers (close to 1 cell/capsule). Furthermore, the most important interfering micro-organisms should be taken into consideration, when testing the performance of detection methods using reference materials. When developing reference materials with the described characteristics, detection methods are needed which give a positive result with one or a few cell(s) of the target organism. While these requirements appear to be fairly obvious, precise statements on method performance are rarely available. Strategies to obtain this information are discussed. Further important aspects are practical considerations when using such reference materials for method evaluation. Statistical procedures can help to obtain the relevant information with a minimum of effort.
Keywords: Reference material; Pathogenic micro-organisms; Test sensitivity; Statistical evaluation
Reference material requirements for laboratories and the role of accreditation bodies by M. Stuart; A. Squirrell; L. Besley (pp. 209-215).
It is now over two years since ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories was published. The standard places increased emphasis on the demonstration of traceability of measurements made by laboratories. In the areas of chemical and biological metrology, the introduction of this standard has brought new challenges for laboratories to grapple with. This paper will examine the requirements regarding traceability for chemical and biological measurements, with specific reference to the use of reference materials by laboratories. This will be explored from the perspective of both accreditation bodies and a laboratory which is both a user and producer of certified reference materials. Moreover, the paper will describe mechanisms that are being used to improve the use of reference materials by accredited laboratories and hence the traceability of measurements. Finally the role of accreditation programs for reference material producers in assisting with this aspect will be examined.
Legal pitfalls of CRM production and distribution by B. M. Gawlik; A. Lamberty; C. L. Klein; T. P. J. Linsinger; J. Pauwels (pp. 216-220).
The huge market of commercially traded chemical substances and their subsequent deliberate or accidental diffusion into the environment has triggered an increase in environmentally related legislation regarding chemical substances. In this context, laboratories require suitable calibration standards and matrix certified reference materials (CRMs) for method development, validation and quality control in order to survey related threshold and limit values. Unfortunately, CRMs are subject to the same technical trade barriers as they should help to overcome. Similar problems exist when the production of a CRM touches intellectual property rights (IPR), e.g. in case of GMOs, or when regionally banned veterinary drugs have to be monitored. Another often under-estimated problem is the liability and legal responsibility of the CRM-producer. This paper discusses different aspects of these legal pitfalls and suggests some approaches to overcome these difficulties.
Keywords: CRM-production; Liabilities; Shipment of reference materials
On the role of environmental reference materials in the development of horizontal standards for environmental protection by B. M. Gawlik; F. Ulberth; H. Langenkamp; G. Bidoglio; M. Grasserbauer (pp. 221-225).
The need for standardisation and harmonisation of measurements increases with the progress of the European integration process. One of the areas for which the need for harmonisation has been emphasised is the protection of the soil compartment. While knowledge of problems associated with soils is increasing in Europe, based on soil surveys, monitoring systems and data networks, the corresponding (analytical) data is not often comparable, which limits its value for policy development. In this context, the European Commission has invited the Member States to investigate the possibility for a harmonisation of European standards in the fields of soil, sludge and biodegradable waste (compost). Furthermore, the development of new reference materials for both the validation of these new methods and their successful implementation on a routine basis is required. This paper shows some selected examples for which the development of horizontal standards may be worth investigating. In addition, it discusses and proposes the vehicle of (C)RMs for the implementation of a common measurement system for soil, related to these horizontal standards. It also raises some open questions and sheds light on future perspectives and challenges.
Keywords: Horizontal standards; CRMs; Support to legislation; Soil protection
Reference material needs for quality assessment of milk and dairy products by Ivano De Noni (pp. 226-231).
Common market organization of milk and dairy products includes regulations intended to guarantee prices and subsidies to some products (e.g. butter and skimmed-milk powder) provided they meet specified compositional requirements. Despite this, only a few reference materials along with robust and easy-to-apply analytical methods to assess the genuineness of dairy products are available. A short description of the problems in establishing authenticity of these products with respect to the available reference materials is presented. Processing innovations and the availability of new ingredients are changing the characteristics of some traditional dairy products. The development of the food policy of the European Union has taken these issues into account by demanding traceability of both finished food and ingredients. Hence, the recognition of product characteristics or processing technology always implies adoption of new analytical approaches along with new reference materials. These requirements demand for more comprehensive knowledge of the food manufacturing chain with special regard to chemical modifications which can be directly related to the quality of the raw materials or the processing conditions. Some analytical approaches considering these requirements as well as the most appropriate characteristics of the related reference material are discussed.
Keywords: Reference material; Dairy product; Quality; Authenticity
Trends in the certification of reference materials by Adriaan M. H. van der Veen (pp. 232-236).
The certification of reference materials is still a rapidly developing area. Mostly driven by demands from laboratories, new reference materials are produced, and even new categories of materials are developed, such as genetically modified organism materials or materials for qualitative analysis. Even in more classical areas, such as the certification of chemicals for purity, there are important new insights, in particular in modelling the measurements and the property values. Laboratories are asking increasingly for uncertainty budgets of reference materials that are compatible with the concepts of the Guide to the expression of uncertainty in measurement, thus putting stronger demands to improve not only the quality of the materials, but also of the science and technology behind a certification. Three important issues are highlighted to exemplify these trends: the further interpretation of homogeneity and stability data, the appreciation of asymmetry due to mathematical constraints (relevant for, e.g., purity and trace analysis), and the certification of reference materials for qualitative measurement.
Keywords: Certified reference material; Certification; Measurement uncertainty; Homogeneity study; Purity
Implementation of traceability – needs and perspective of the in-vitro-diagnosticum industry by Emil Völkert (pp. 237-238).
Manufacturers support the concept of traceability. However, only a small number of the medically relevant measurands can be traced to the highest metrological order. In many cases, the measured substances are heterogeneous mixtures where traceability can be established only to either an international conventional reference measurement procedure or to a manufacturer’s own in-house reference system. The traceability concept needs to be seen in the context that the results of medical laboratories are not an aim per se, but are meant to provide useful medical information to clinicians, and that pre- and post-analytical steps may also contribute significantly to errors. There is a need for the further development of suitable reference measurement systems, but in view of the multitude of tasks and limited resources, priorities need to be set.
Keywords: Traceability; Reference systems; International standards
Reference material needs in clinical laboratory science by Mary M. Kimberly (pp. 239-241).
In 1968, clinical chemistry was considered to be the field most in need of certified reference materials (CRMs). While significant progress has been made in this area, new diagnostic assays are continually being developed that create a need for new CRMs. Members of the clinical laboratory community help to identify reference material needs. Professional and governmental organizations, such as IFCC, AACC, NCCLS, CDC, and the national metrological institutes (NMIs), respond to develop protocols and materials. Several measurands are presented as examples. In the late 1950s and early 1960s, in response to a need for standardization of lipid and lipoprotein measurements, CDC developed a reference system that included secondary reference materials. Over the years, the process of preparation of these materials was refined, eventually leading to the development of NCCLS guideline for preparation of commutable frozen serum pools for use as secondary reference materials (C37-A). This protocol was used for the preparation of NIST SRM 1951a (lipids in frozen (liquid) human serum). In the 1980s, a need for a reference material for blood lead was identified. CDC and NIST cooperated to develop SRM 955 (lead in bovine blood). More recently, efforts have been initiated to standardize high-sensitivity C-reactive protein (hsCRP) assays. In this case, a CRM for CRP existed (CRM 470, developed by IFCC and available from IRMM), but at concentrations in the acute phase reactant range and not in the low range needed for hsCRP assays. CDC coordinated a study to evaluate diluted CRM470 and other candidate materials as secondary reference materials for hsCRP assays.
Keywords: Commutability; JCTLM; Reference materials
Ion chromatography performances evaluated from the third AQUACON freshwater analysis interlaboratory exercise by R. Mosello; G. A. Tartari; A. Marchetto; S. Polesello; M. Bianchi; H. Muntau (pp. 242-246).
This paper describes a collaborative interlaboratory exercise for freshwater analysis held in the framework of the “Analytical Quality Control and Assessment Studies in the Mediterranean Basin Project” (AQUACON). Two sample types were prepared and distributed: the first for the analysis of pH, conductivity and major ions (calcium, magnesium, sodium, potassium, chloride, sulphate, bicarbonate) and the second for algal nutrients (ammonium, nitrate, phosphate, total phosphorus and total nitrogen, silicate). Two solutions with different concentration levels were prepared for each of the samples; homogeneity throughout bottles and stability of samples in time were tested from the two organising laboratories. Results were obtained from 155 laboratories from 30 countries around the world. A detailed examination of results obtained by ion chromatography showed that an important source of error was the neglect of the non-linearity of calibration curves. Repeatability and reproducibility tests were performed in a selected number of experienced laboratories in accordance with the ISO standard 5725 for anion and cation ion chromatography determination. The best obtainable repeatability and reproducibility limits of IC methods of water analysis are about 5 and 10%, respectively.
Keywords: Ion chromatography; Repeatability; Reproducibility; Freshwater analysis; Analytical Quality Control; Intercomparison
Teaching reference material preparation: the PHARE-country experience by H. Muntau; B. M. Gawlik; A. Sahuquillo; M. Bianchi; A. Rehnert (pp. 247-252).
The paper presents an overview about the outcome of two hands-on courses on environmental reference material production organised by the European Commission’s Environment Institute within the context of its PHARE-AQUACON activities. Two plant reference materials, i.e. TP-28 (black tea) and TP-29 (mallow) were prepared and characterised by the course participants. Data on homogeneity and information values about the contents of inorganic and organic pollutants are presented. Furthermore, information about the AQUACON-Project are given, too.
Keywords: Environmental reference material production; PHARE-AQUACON
Method validation and reference materials by Margreet Lauwaars; Elke Anklam (pp. 253-258).
For implementation of food and feed legislation, there is a strong need for development and harmonisation of reliable, validated and if possible, robust and simple analytical methods. In addition, precise methods used for measuring the exposure of humans to certain types of food contaminants and residues (natural, man-made or produced during technological treatment) such as, e.g. mycotoxins, acrylamide, pesticides and allergens have to be available, in order to compare results derived from monitoring studies. Methods should be validated (in-house or in a collaborative trial) according to harmonised protocols and good laboratory practice must be in place in order to be compliant with internationally harmonised standards. The way in which this is implemented depends strongly on the analyte, interference within the food matrix and other requirements that need to be met. Food and feed certified reference materials, when matrix matched and containing the appropriate concentration of the certified substance, are an extremely useful tool in validation of measurements.
Keywords: Food analysis; Food safety and quality; Method validation; Certified reference materials
Inter-comparison exercises as a tool for teaching quality assessment: an experience in Spanish universities by A. Sahuquillo; R. Compañó; R. Rubio; G. Rauret (pp. 259-265).
Since the academic year 2001–2002, inter-laboratory trials for students of Analytical Chemistry in Spanish Universities have been organised by the Department of Analytical Chemistry at the University of Barcelona in collaboration with the Complutense University of Madrid, the University of Cordoba and the University of Huelva. The aim of these exercises is to train students in the use of tools for the assessment and improvement of quality in analytical laboratories.Representative samples of environmental and food analysis, agricultural soils and a type of beer were selected. The ethanol content of the beer and the pH, conductivity, and extractable phosphorus and potassium content in the soil were the chosen analytical parameters.Sample preparation, homogeneity and stability studies, as well as the statistical treatment of data from participants, were carried out by the laboratory Mat Control of the Department of Analytical Chemistry of the University of Barcelona.The paper presented heregives the results obtained after two years of experience.
Keywords: Inter-comparison exercises; Proficiency testing; Quality system; Quality control materials; Teaching; Education
Analytical requirements and the improvement of quality of the measurement results
by Fernando Cordeiro (pp. 266-267).
The EC networking on elemental speciation revisited by R. Cornelis; W. Buscher; M. Sperling; O. F. X. Donard; N. Proust; E. Rosenberg; R. Milacic (pp. 268-271).
In Europe, the EC-funded Thematic Network “Speciation 21” was instrumental in disseminating the existing knowledge about chemical speciation of trace elements. It created a forum in which analytical chemists working in method development were mixed with potential users from industry and representatives of legislative bodies. This endeavour is continuing in the currently established European Virtual Institute for Speciation Analysis (EVISA). Although there already exists substantial know-how in Europe for the speciation of a number of substances, such as organo-arsenic, organo-tin and organo-mercury compounds, to name just these three groups, there is an urgent need to enforce the analytical potential in speciation analysis on a much wider scope of compounds capable of providing data of a suitable quality. The ensuing need for quality assurance of the analytical procedures requires the analysis of representative reference materials, certified for the relevant species. Last but not least, where applicable, the European-wide legislation should be adapted to focus on toxic species of the elements, rather than the total element.
Keywords: Elemental speciation; Speciation 21; EVISA; Certified reference materials; Legislation; Environment
Mat Control: a new laboratory for the preparation of reference materials at the University of Barcelona, Spain by A. Sahuquillo; E. Carrasco; H. Muntau; R. Rubio; G. Rauret (pp. 272-277).
With the aim of responding to the growing demand for quality control materials (QCMs) in Spain for routine analysis and use in proficiency testing schemes, a research group of the Analytical Chemistry Department of the University of Barcelona built up a fully equipped laboratory for preparing reference materials. This article discusses the background of the group, the design and description of the laboratory, the production and working plan, as well as a summary of the results obtained from the activities of the laboratory Mat Control since its creation in 2001.
Keywords: Reference materials; Quality control materials; Proficiency testing; Quality system; Production