Certified reference materials for inorganic and organic contaminants in environmental matrices

Chemical measurements often constitute the basis for informed decision-making at different levels in society; sound decision-making is possible only if the quality of the data used is uncompromised. To guarantee the reliability and comparability of analytical data an intricate system of quality-assurance measures has to be put into effect in a laboratory. Reference materials and, in particular, certified reference materials (CRMs) are essential for achieving traceability and comparability of measurement results between laboratories and over time. As in any other domain of analytical chemistry, techniques used to monitor the levels and fate of contaminants in the environment must be calibrated using appropriate calibration materials, and the methods must be properly validated using fit-for-purpose matrix-matched CRMs, to ensure confidence in the data produced. A sufficiently large number of matrix CRMs are available for analysis of most elements, and the group of chemicals known as persistent organic pollutants, in environmental compartments and biota. The wide variety of analyte/level/matrix/matrix property combinations available from several suppliers enables analysts to select CRMs which sufficiently match the properties of the samples they analyse routinely. Materials value-assigned for the so-called emerging pollutants are scarce at the moment, though an objective of current development programmes of CRM suppliers is to overcome this problem.     

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     

An overview of laboratory performance studies conducted by the IAEA for marine pollution studies of metals and organic contaminants

Aspects of the International Atomic Energy Agency (IAEA) Analytical Quality Control Services (AQCS) for marine environmental studies are discussed, focusing on recent laboratory performance studies (LPS) and the production of reference materials for trace metals and organic compounds in various marine matrices. The IAEA has organized seventeen global interlaboratory studies for a range of organic contaminants. Of note has been the inclusion of numerous polychlorinated biphenyl congeners (PCBs) and some sterols of anthropogenic origin. Concurrently, there have been eleven worldwide intercomparison exercises for trace metals in the marine environment, most of which included methylmercury. Although such interlaboratory studies can help improve performance in individual laboratories and regional laboratory networks, the results reveal that problems remain in the determination of some metals and many organic contaminants.     

Traceable measurements in clinical laboratories

 Reliable, traceable and comparable measurements provide the rational basis for evaluation of the quality of a result and the starting point for recognized laboratory accreditation in any national area. Modern medical diagnostics and treatment involve rapidly rising numbers and types of clinical laboratory measurements, that are reliable. Therefore, the basic principles to be followed to assure the traceability of clinical measurements as required by the Romanian Laws of Metrology are reviewed. Main sources affecting the quality of the unbroken chain of calibrations that relate the measurements back to appropriate measurement standards are discussed. Examples of how to achieve traceable measurements in clinical laboratories are presented. Details of specific uses of reference materials, measuring instruments and standard measurement methods are also discussed. Received: 8 January 1998 · Accepted: 21 April 1998     

鱼肉环丙沙星标准样品的研制

介绍了以鲤鱼鱼肉作为基质含有环丙沙星的标准样品的研制过程。通过添加环丙沙星养殖鲤鱼获得样品,用液相色谱-串联质谱法对样品进行均匀性和稳定性检测,采取8个实验室协作定值的方法对样品进行定值检测,进行了标准值的计算和不确定度评估;研究表明获得的样品均匀性良好,稳定性至少17个月,可以用于检测质量控制和科研工作。     

Quality assurance in biological monitoring of environmental exposure to pollutants: from reference materials to external quality assessment schemes

The presence of chemicals in the environment is a matter of concern in that it poses potential health risks. At present, exposure to toxic chemicals and their biological and biochemical effects can be better estimated by biological monitoring, through the systematic collection of specimens from potentially exposed humans. Biological monitoring of human exposure to environmental pollutants is hampered by the difficulty to assess data reliability. As a consequence, the validity of biological monitoring should depend on the strict implementation of a quality assurance (QA) program, which includes a series of procedures aiming to ensure that laboratory results meet defined standards of quality and are reliable. For the validation and monitoring of methods’ performance, to ensure the trueness of measurements and to warrant the traceability to international standards, reference materials (RMs) and certified reference materials should be used. Internal quality control and external quality assessment (EQA) are part of overall QA and are carried out to verify that analytical errors are compatible with the specific requirements or needs of the user. In particular EQA schemes (EQAS) allow to test independently the analytical performance of participating laboratories. In the last decades, increasing concern has been raised by urban air pollution; lead and benzene, two gasoline components released by motor vehicle exhausts, are known to be toxic to humans. For biological monitoring of lead exposure of the general population, screening campaigns, utilizing lead in blood as a biomarker, have been carried out since the 1970s. Strict strategies were adopted to ensure data comparability, including the preparation of RMs, the organization of EQAS and the cross-exchange and analysis of blood samples between laboratories. Biological monitoring of benzene exposure could be carried out by means of various biomarkers such as benzene in blood and benzene, trans,trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA) in urine. At present, few RMs and EQAS are available for these biomarkers. A pilot EQAS for t,t-MA in urine, adopted to assess the reliability of data regarding benzene exposure, has been organized and carried out between 1996 and 1997 in Italy. From the accrued experience, it clearly emerges the importance of strategies designed to guarantee the quality of biological monitoring data. The use of RMs and the participation in EQAS are highly recommended in order to improve the global performance of methods and laboratories involved in biological monitoring.     

Determination of Trace Metals in Woodlice and their Skins with Particular Emphasis on Quality Control

AI, Fe, Mn and Zn were determined in two ditTerent species of woodlouse: Porcellio scaber and Porcellio dilalalus. Both species were cultivated under standardized conditions in a climatic chamber. Moreover, skins of the cultivated animals were collected and analyzed separately to examine a possible way of decontamination by moulting. To obtain enough sample material for each species, IS animals of the same age and size were pooled. For skin analysis, 10–12 skins were collected and pooled. The animals and their skins were dried, ground and digested in pure concentrated nitric acid using multiwave-assisted high-pressure digestion and. finally, analyzed by ICP-OES. Special emphasis was given to quality control: the reference materials Dorm-2, Dogfish Muscle (Squalus acanthias) and SRM 1577b Bovine Liver, were used to evaluate the whole analytical process including sample digestion. These reference materials of animal origin were selected to match the matrix of the samples as closely as possible. While concentrations of Fe. Mn and Zn were traced to both reference materials, the concentration of AI was checked by Dorm-2 only. Analyses of the elements in the reference materials were carried out using four ditTerent wavelengths for each element simultaneously. aiming at the determination of the best suited wavelength for each element. Analyses of woodlouse samples and their skins were finally carried out using the wavelengths with the highest sensitivities after absence of spectral interferences had been demonstrated.     

Measurement traceability and US IVD manufacturers: the impact of metrology

A goal of clinical laboratory science is to produce accurate and comparable patient test results for a specimen independent of analytical methodology. The In Vitro Diagnostics Directive in Europe has provided the impetus for the U.S. in vitro diagnostic (IVD) industry to adapt the concepts of Metrology, the science of measurement, including measurement traceability and measurement uncertainty. The joint committee for traceability in laboratory medicine has provided a valuable database of internationally recognized reference materials and methods and reference laboratories. Much of the responsibility for measurement traceability falls on IVD manufacturers, but all global stakeholders, including the clinical laboratory profession, government Regulatory bodies, metrology institutes, and the providers of EQA/PT surveys, must cooperate to progress toward this goal. The adaptation of the concepts of Metrology to the clinical laboratory is an appropriate and logical development and it will continue in the twenty-first century.     

Development of reference materials for microbiological analysis

The reliability of reference materials (RMs) depends on properties such as fitness, robustness, commutability, stability and homogeneity. The development of RMs for microbiological analysis is especially challenged through questions around the stabilisation and recovery of viable cells, the dispersion of precise numbers of cells, matrix effects and, when using molecular techniques, the presence of nucleic acids (e.g. DNA) of dead and live target organisms. However, RMs are indispensable tools for quality control in microbiological analysis. The Institute for Reference Materials and Measurements (IRMM), as part of the European Commission, concentrates its efforts on the development of RMs to support the development, implementation and monitoring of EU legislation. A special focus is given to highly precise RMs for presence/absence and enumeration tests in microbiological food and water analysis. Another group of new RMs certified by the IRMM comprise DNA-based materials to control the identity of micro-organisms in qualitative assays. All of these activities serve to improve quality control in microbiological analysis. Presented at ‘BERM-10’, April 2006, Charleston, SC, USA.     

Energy Storage Properties of Phase Change Materials Prepared from PEG/CPP

Latent heat storage is one of the most efficient ways of storing thermal energy.Unlike the sensible heat storage method,the latent heat storage method provides much higher storage density,with a smaller temperature difference between storing and releasing heat.Phase change materials(PCMs)can be used for energy storage and temperature control1,2.Among them,the solid-solid phase change materials are focus of attention3,4.They can be applied in many fields such as solar energy utilization,waste…     

Organic Thermoelectric Materials as the Waste Heat Remedy

The primary reason behind the search for novel organic materials for application in thermoelectric devices is the toxicity of inorganic substances and the difficulties associated with their processing for the production of thin, flexible layers. When Thomas Seebeck described a new phenomenon in Berlin in 1820, nobody could have predicted the future applications of the thermoelectric effect. Now, thermoelectric generators (TEGs) are used in watches, and thermoelectric coolers (TECs) are applied in cars, computers, and various laboratory equipment. Nevertheless, the future of thermoelectric materials lies in organic compounds. This paper discusses the developments made in thermoelectric materials, including small molecules, polymers, molecular junctions, and their applications as TEGs and/or TECs.     

有机化学知识在高分子材料合成创新实验中的运用——分享几个实例

针对目前教学中存在的理论课程之间、实验课程与理论课程之间关联不够紧密等问题,探索了通过"知识关联"将有机化学基本知识运用到高分子材料合成创新实验中的教学思路。以新试剂合成及应用、荧光聚酯合成、聚酰胺合成、聚酯水解等为例,介绍了如何将有机化学新理论、新方法、新试剂应用于本科高分子化学和高分子材料实验教学,以及如何将有机化学的理论知识和实验手段应用于高分子材料合成教学中。实践表明:通过"知识关联",将有机化学基础理论知识和实验技能应用于高分子合成实验中可以提高学生对所学知识的理解和运用能力,增强学生的实验探索兴趣,有效改进了高分子材料合成实验教学的课堂气氛。     

Reference material needs in clinical laboratory science

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.Presented at BERM-9—Ninth International Symposium on Biological and Environmental Reference Materials, June 15–19, 2003, Berlin, Germany.     

Reference materials for the radionuclide program – performance evaluation samples

 The U.S. Food and Drug Administration's (FDA) Radionuclides in Food Program was reinstituted in 1973, expanded in 1975 and again in 1990, to its present status. The need for reference materials for radionuclides in food samples was recognized as early as 1962. There were no available reference materials for these types of samples at that time. The materials developed to assure that the results being obtained were acceptable were primarily milk, water and food. The radionuclides of interest were iodine-131, cesium-137 and other short-lived radionuclides found in fission products. These were first issued through the then Health, Education and Welfare Department's Analytical Quality Control Program and, later, in 1970 through the Environmental Protection Agency (EPA). In November 1998, the EPA discontinued this program. The FDA is proposing to reinstitute part of this program, as a primary laboratory, traceable to the National Institute of Technology (NIST) and included in this, the FDA proposes to supply the States and/or their contractors with low-level standards and with milk- and water intercomparison samples. It will also use these results where possible as collaborative studies to validate some of the more recent methods adopted by the American Society for Testing and Materials (ASTM), American Public Health Association (APHA) and Association of Official Analytical Chemists International (AOAC, Int'l.) The FDA will also supply low-level standards to compliment these programs as did the EPA. It is expected that these samples will serve as performance evaluation samples for the States programs.     

Accreditation of reference material producers

 The use of reference materials is the most pragmatic means by which the analyst can achieve comparability of data. Reference material producers therefore need to have adequate quality systems in place for ensuring the reliability of their materials. In order to provide guidance to both producers and assessors, ISO Guide 34 has recently been produced detailing the quality system requirements for the production of reference materials. CITAC, REMCO and ILAC are now collaborating in the revision of this guide to produce a free-standing document detailing the general requirements for the competence of reference material producers. This paper discusses some of the more important issues described in these documents. The possible formation of an international register containing details of a reference material producer's quality system status is also discussed.     

Quantifying the release of polymer additives from single-use materials by respiration activity monitoring

Single-use technologies, and thereby polymer materials, are increasingly applied in laboratory and large-scale fermentations. However, little is known about how leaching of polymer additives may affect the culture and compromise GMP regulations. The aim of this study is to introduce a standardized analytical device to test the biocompatibility of such polymer materials. The breathing behavior of various microorganisms was determined with the Respiration Activity MOnitoring Systems (RAMOS) as a function of the added amount of polymer commonly applied in biotechnology. Nylon and polyamide 12, used in cable ties and tubing, respectively, were found to delay and inhibit microbial growth. This is caused by leaching of the plasticizer N-butylbenzenesulfonamide and monomer 1,8-diazacyclotetradecane-2,7-dione, respectively, from the polymers. A metabolic activity inhibition threshold concentration between 4–10 g/L was determined for polyamide 12 tubing. In conclusion, RAMOS is a sensitive and time-effective device to qualify materials before they are applied in cultures.     

有机-无机杂化氧化硅基介孔材料

有机基团可以通过嫁接或共聚的方法引入到氧化硅基介孔材料的孔表面或材料的骨架中,形成表面结合型和桥键型两大类有机-无机杂化氧化硅基介孔材料.本文综述了有机-无机杂化氧化硅基介孔材料的最新研究进展,介绍了其合成方法、应用及潜在的应用领域,详细总结了目前已报道的有机-无机杂化氧化硅基介孔材料的种类,展望了桥键型有机-无机杂化氧化硅基介孔材料的发展及应用前景.     

Clinical reference materials for the validation of the performance of photometric systems used for clinical analyses

 There are a wide variety of spectrophotometric devices nowadays used in health services with various qualities of manufacture methods of measurement and metrological characteristics for performing the necessary measurements. Therefore, to meet the accuracy and repeatability requirements needed in medical diagnosis and treatment, the validation of the performance of such systems by clinical chemistry laboratories is essential. However, the validation of a spectrophotometric system for clinical analyses requires several reference materials, according to the end use of the measurement results. This paper discusses some characteristics required of the clinical reference materials needed and used by Romanian Institute of Metrology for validation work. Types of clinical reference materials developed in the national area for this purpose are also presented. Received: 23 April 1997 · Accepted: 7 July 1997     

Controlled Chemical and Drug Delivery via the Internal and External Surfaces of Layered Compounds

Abstract

We demonstrate, and review the very small, but growing body of literature regarding a recently discovered application of layered compounds, which involves the ability of layered materials to sequester and later release molecules of chemical and biological significance. The application relies upon intercalation chemistry; a reversible process whereby atoms, molecules, macromolecules, and polymers may be inserted into the interstices of a layered matrix. We demonstrate that layered materials are able to effectively getter water‐soluble atoms and molecules from aqueous dispersions, and further demonstrate that the absorbed molecules can be later released from the interlayer region to perform a desired chemical function. Work in our laboratory involving the application of layered hybrid materials in photographic media is described in detail and we establish two general release mechanisms whereby intercalated functional chemistry can be first sequestrated and later delivered via a chemical switch to perform a desired function. The process has enormous potential as a general method for the controlled, temporal release of materials of chemical and biological significance.     

Accreditation and the need for certified reference materials

The comparability of data from accredited laboratories is not always as good as customers would desire. A number of reasons for this fact are given. Clients of laboratories do not specify methodology, which may lead to the application of systematically different methods or to methodology with improper performance characteristics. Laboratories do not always validate methodology sufficiently which is, however, among others provoked by a lack of reference materials. It is argued that accreditation cannot enforce comparability on itself, but needs to be embedded in a measurement infrastructure. The quality systems which underly accreditation form a basic element. In addition, adequate methods, good laboratory performance studies and certified reference materials are required.