The role of reference materials in the analytical laboratory

Summary Importance, definition, preparation, characterization, selection and use of reference materials in the analytical laboratory are discussed in general.

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Die Rolle der Referenzmaterialien im analytischen Laboratorium

Zusammenfassung Bedeutung, Definition, Herstellung, Charakterisierung, Auswahl und Verwendung von Referenzmaterialien im analytischen Laboratorium werden allgemein diskutiert.

     

Preparation of twelve candidate agricultural reference materials

Summary A cost-effective approach to monitoring and maintaining reliability of analytical procedures is by the incorporation of appropriate, compositionally similar reference materials into the scheme of analysis. Agricultural and food commodities represent an extremely wide range of composition, in respect of the sought-for analyte and the supporting material (matrix), not fully reflected in currently available biological reference materials (BRM's). With the view to attempting to fill some of the gaps in the world repertoire of reference materials and to have suitable products for our laboratories' use, preparation has been completed of twelve candidate agricultural reference materials. These products, representing a number of food classes, include bovine muscle powder, hard red spring wheat flour, soft winter wheat flour, durum wheat flour, wheat gluten, corn bran, corn starch, potato starch, whole egg powder, whole milk powder, microcrystalline cellulose, and sugar. Preparative steps included, as required, freeze drying, grinding or ball milling, X-ray sterilization, sieving, blending and packaging to yield sizeable quantities of each material in finely powdered form. Cooperative analytical effort is expected to lead to characterization in respect of concentrations of a number of nutritionally, toxicologically and environmentally-pertinent, major, minor, and trace chemical elements. These materials will then be available for analytical chemical data quality control for inorganic constituents in a range of agricultural commodities.

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Herstellung von zwölf als landwirtschaftliche Referenzmaterialien vorgeschlagenen Substanzen

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Contribution No. 88-49 from Land Resource Research Centre     

Untersuchung von Thallium in Rohstoff- und Umweltproben

Zusammenfassung Unterschiedliche authentische Proben wie Brennstoffe, Steine, Erden, Erze, Zwischenprodukte, Abfallstoffe und Umweltproben wurden auf Thallium untersucht. Ausgehend von den dokumentarisch zusammengestellten Untersuchungsergebnissen dieser Materialien werden die Probleme der Probenvorbereitung und Analyse diskutiert. Hierbei zeigte sich z. B., daß zur Anreicherung des Thalliums die Verdampfungsanalyse bei ca. 1200°C nicht für alle Fälle geeignet ist, da durch bestimmte Effekte Minderbefunde auftreten können. Es werden daher verschiedene Aufschluß-verfahren mit den sich anschließenden Trennungsmethoden vorgestellt. Als analytische Meßverfahren wurden die AAS und die Inversvoltammetrie eingesetzt. Über Erfahrungen bei der Anwendung dieser Methoden wird berichtet.

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Determination of thallium in raw materials and environmental samples

Summary Various authentic samples (fuels, rocks, soils, ores, intermediate products, waste materials, environmental materials) were examined for their thallium content. Based on the compiled analytical results, the problems of sample preparation and analysis are discussed. It became obvious, e.g., that the vaporization analysis at about 1200°C is not in all cases suitable for the preconcentration of thallium as certain effects might lead to lowered results. Therefore, different decomposition techniques with the subsequent separation procedures are presented. The analytical determination was performed by atomic absorption spectrophotometry and inverse voltammetry, according to concentration. Experiences gathered with these methods are reported.

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Herrn Prof. Dr. W. Fresenius zum 70. Geburtstag gewidmet     

NBS activities in biological reference materials

Summary NBS activities in biological reference materials during 1986–1988 are described with a preview of plans for future certifications of reference materials. During the period, work has been completed or partially completed on about 40 reference materials of importance to health, nutrition, and environmental quality. Some of the reference materials that have been completed during the period and are described include: creatinine (SRM 914a), bovine serum albumin (SRM 927a), cholesterol in human serum (SRM's 1951–1952), aspartate aminotransferase (RM 8430), cholesterol and fat-soluble vitamins in coconut oil (SRM 1563), wheat flour (SRM 1567a), rice flour (SRM 1568a), mixed diet (RM 8431a), dinitropyrene isomers and 1-nitropyrene (SRM 1596), and complex PAH's from coal tar (SRM 1597). Oyster tissue (SRM 1566a) is being analyzed and should be available in 1988.

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NBS-Aktivitäten in biologischen Referenzmaterialien

     

The role of statistics in quality assurance

Summary The quality of data, which is to say its accuracy, must be known whenever it is to be used for purposes of decision. This is only possible as it is produced by a valid analytical system operating in a state of statistical control. A quality assurance program should be established, consisting of quality control of the analytical system and quality assessment of the data that are produced. Data quality objectives should be established for every measurement situation and the accuracy attained must be within these limits. Ideally, the attained accuracy should exceed the required accuracy by a factor of three, at a minimum. The estimation of attained accuracy is best made using reliable reference materials. When they are not available, spikes may be used with lesser confidence. No matter what estimation techniques are used, decisions must be made on the basis of statistical tests of significance. The evaluation of accuracy is a continuing operation and facilitated by the use of appropriate control charts. The paper discusses the above described concepts and summarizes the techniques most useful for evaluating the accuracy of analytical data.

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Die Rolle der Statistik in der Qualitätssicherung

     

Analytik in der Aufgabe praktischer Umwelt-Politikberatung

Ohne Zusammenfassung

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The role of analytical chemistry in practical environmental politics

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Herrn Prof. Dr. G. Tölg zum 60. Geburtstag gewidmet     

Preparation of lipids from plant and animal tissues: Pure compounds and reference mixtures

Summary The systematic analysis of complex lipid mixtures is based on the consecutive application of complementary principles of chromatography. Pure compounds, synthetic standard mixtures, and biological lipid extracts are required as reference materials. Procedures for the preparation of individual compounds and standard mixtures are outlined, and recommendations are offered regarding the choice of biological reference materials and their certification.

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Gewinnung von Lipiden aus pflanzlichen und tierischen Geweben: reine Verbindungen und Referenzgemische

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In this article, lipids have been named according to the Recommendations of the IUPAC-IUB Commission on Biochemical Nomenclature (see Eur J Biochem (1977) 79:11–21)     

An interlaboratory study to improve the quality of chemical and biological measurements in waste water

 Analyses of waste water are routinely performed to monitor the level of contamination. To verify the quality of such determinations the National Institute of Chemistry, with the support of the Ministry of Environment and Spatial Planning and the Slovenian Accreditation Agency, organizes interlaboratory comparisons. Over the last 3 years, five interlaboratory trials named "MPP-Waste Water" were organized. Each round attracted around 50 participants, mostly from Slovenia and some from abroad, which enabled the testing of SIST ISO methods or alternative methods. We prepared samples for determination of harmful substances that are important for the characterization of waste water; physico-chemical parameters (pH), global parameters – chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), metals (mercury, cadmium, copper, nickel, lead and chromium (VI)), nutrients (ammonia and total phosphorus), anions (chloride, nitrite, nitrate, sulphate) and toxicity to Daphnia magna. For the analysis of each parameter we prepared two samples at two different concentration levels. The materials used in the proficiency testing were carefully prepared and their homogeneity and stability were verified. The purpose of this scheme was to enable participants to check their day-to-day analytical performance. The results should enable the participants to improve the quality of their analyses.

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Received: 24 October 2002 Accepted: 2 January 2003

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Acknowledgments We would like to thank the Ministry of Environment and Spatial Planning and the Ministry for Education, Science and Sport for providing financial support. We would like to thank members of the Technical Committee: Mrs. Marjana Kovacˇicˇ, Dr. Katja Otrin-Debevc, Prof. Dr. Marjan Veber and Mrs. Boža Gregorc for their valuable support. Special thanks are due to Dr. Adrian Van der Veen who helped us in running the first PT.

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Presented at CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia

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Correspondence to M. Cotman     

Characterization of high-purity aluminium

Summary The state of the art in characterization of high-purity aluminium, including activation analysis, glow discharge mass spectrometry (GDMS) and wet chemical multistep procedures has been described. It has been shown on the basis of comparative tests, in which laboratories in Europe, Japan and USA have participated, that with regard to power of detection as well as reproducibility even at levels below 500 ng/g neutron activation analysis (INAA, RNAA), wet chemical multistep procedures and GDMS can contribute to the characterization of high-purity aluminium. The measurement of the resistivity ratio have proved as a suitable test for the integral content of dissolved impurities. H at levels of 0.3 g/g can be measured by vacuum solid extraction or carrier gas fusion. For a complete and optimal characterization of high-purity aluminium all these methods are needed and should periodically be checked against each other.

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Charakterisierung von hochreinem Aluminium

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Thanks are expressed to VAW High-Purity Metal Division for allowing of publishing the foregoing results and financial support.     

A new approach to the preparation of biological reference materials for trace metals

Summary Preparation and certification of a new, nondefatted biological reference material (RM) for trace metals is reported. LUTS-1 is a homogeneous slurry of lobster hepatopancreas containing 85% (w/w) moisture and 8.2% (w/w) lipids (55% dry weight basis). This RM should prove of considerable use in validating analytical procedures involving faunal field samples containing significant lipid content.

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Neue Methode zur Herstellung von biologischen Referenzmaterialien für Spurenmetalle

     

Fluorine determination in different vegetal tissues

Summary A method for the preparation of different vegetal samples has been described. An analytical method is also pointed out, which, for reproductivity, accuracy and execution rate, is the best suited to monitoring of environmental fluorine.

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Fluorbestimmung in verschiedenen pflanzlichen Geweben

Zusammenfassung Ein Verfahren zur Vorbereitung verschiedener pflanzlicher Proben wurde beschrieben. Deren analytische Untersuchung eignet sich gut für die Ermittlung von Fluor in der Umgebung.

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Communication presented to the European Conference on Analytical Chemistry Euroanalysis V, Cracow/Poland, August 26–31, 1984.     

Benthic chamber chemistry

Summary The release of pollutants and natural constituents from the sediments to the bottom water is an important flux measurement which is required in order to establish the turnover of substances and trace metals in the marine environment. The article summarizes the benthic chamber technique and the analytical methods used to establish the chemical reactions that occur in the bottom water and the top layer of the sediments. Two results illustrate the effect of benthic organisms on the release rates.

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Chemie der Benthalkammer

Zusammenfassung Zur Beurteilung des Umsatzes von Substanzen und Spurenmetallen im Meer ist es von Bedeutung, die Freisetzung von Verunreinigungen und natürlichen Bestandteilen aus den Sedimenten in das Bodenwasser zu messen. Die Technik der Benthalkammer wird zusammenfassend dargestellt und die analytischen Methoden erwähnt, die zur Aufklärung der chemischen Reaktionen im Bodenwasser und der oberen Sedimentschicht benutzt werden. An zwei Beispielen wird die Wirkung von Benthalorganismen auf die Geschwindigkeit der Freisetzung gezeigt.

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This article is dedicated to Professor Wilhelm Fresenius, who for decades has skillfully promoted the science of analytical chemistry, on the occasion of his 70th birthday     

Quantitative studies on asbestos pollution with a combination of light and electron microscopy

Summary An analytical procedure for the quantitative assessment of asbestos pollution in air, water and biological materials is described. The characterization steps consist of the determination of the total number of fibers in a sample with phase contrast light microscopy and the identification of a significant fraction of those fibers with quantitative X-ray analysis in a scanning transmission electron microscope (STEM). The total procedure enables the economic and accurate determination of the content of asbestos (classified in 5 species and other fibrous materials) in a particular material. The application of this combination technique for medical studies is described. A comparison with other analytical techniques used for asbestos studies is included.

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Quantitative Asbest-Belastungsstudien mittels einer Kombination von Licht- und Elektronenmikroskopie

Zusammenfassung Es wird ein analytisches Verbundverfahren für die quantitative Erfasssung der Asbestbelastung in Luft, Wasser und biologischen Materialien beschrieben. Es beruht auf Verwendung der Lichtmikroskopie zur Bestimmung der Gesamtfaserzahl in einer Probe und der Elektronenmikroskopie mit quantitativer Röntgenmikroanalyse zur Identifizierung der Fasern. Das Verbundverfahren ermöglicht die kostengünstige Ermittlung des Asbestgehaltes (klassifiziert in 5 Asbestarten, sowie andere faserförmige Materialien) mit guter Richtigkeit. Die Anwendung der Methode für medizinische Studien wird beschrieben. Weiterhin wird das Verbundverfahren mit gängigen anderen Bestimmungsmethoden für Asbest verglichen.

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday     

Ion-implanted reference standards for use in microchemical analysis of materials

Summary A concise overview has been given of the present state of development of ion-implanted reference standards for the calibration of instrumental methods of microchemical characterization of solid materials.

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Ionen-implantierte Standardpräparate für die Mikroanalyse

Zusammenfassung Der gegenwärtige Entwicklungsstand ionenimplantierter Standardpräparate für die Eichung instrumenteller Mikromethoden der chemischen Feststoffanalyse wurde besprochen.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Characterization (certification) of Corn Bran (NIST RM 8433), Corn Starch (NIST RM 8432) and Microcrystalline Cellulose (NIST RM 8416) Reference Materials for essential and toxic major, minor and trace elemental constituents

Summary Corn Bran (NIST RM 8433), Corn Starch (NIST RM 8432) and Microcrystalline Cellulose (NIST RM 8416) Reference Materials were characterized for essential and toxic major, minor and trace elemental composition in an interlaboratory cooperative characterization campaign. Extensive application of widely varied analytical methods by analysts in cooperating laboratories yielded 10–29 best estimate and 1–16 informational concentration values for each of these materials. Two materials, Corn Starch and Microcrystalline Cellulose, contain particularly low levels of trace elements. These reference materials are intended for analytical quality control of elemental determinations in corn and plant products as well as other agricultural/food materials with related matrices.Contribution No. 92–146 from Centre for Land and Biological Resources Research     

New developments in trace element analysis in the life sciences

Summary In the analysis of trace elements in biological materials it has become more and more apparent that there is often a need not only to determine the levels of the elements in the whole sample but also to measure the element contents in fractions of the materials, such as certain types of cells, subcellular components and molecules. Furthermore, it is sometimes necessary to relate the elemental data to relevant biological and biochemical parameters as there is otherwise a danger that wrong conclusions may be drawn. In this paper these trends in trace element analysis are described with the help of examples and the problems which can occur in the various steps of sampling and sample preparation are discussed.

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Neue Entwicklungen bei der Spurenelementanalyse in den Biowissenschaften

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Reference materials in environmental trace organic analysis

 The paper reviews the application of reference materials (RMs) in environmental analysis of trace organic pollutants. The problems related to RM preparation, stability, use, etc. are critically discussed. Importance of analytical quality assurance and the role RMs play in the process are emphasised. Received: 18 May 1999 · Accepted: 27 December 1999     

Automation in und mit der Analytischen Chemie

Ohne Zusammenfassung

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Automation in and with analytical chemistryV. Classification of working ranges in analytical chemistry with regard to computers

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Teil IV: diese Z. 256, 7 (1971)     

Biosensors based on native chemoreceptors

Summary The coupling of intact natural chemoreceptor structures to potentiometric electrodes results in a new class of electrochemical biosensors with exceptionally fast dynamic response properties and attractive analytical limits. The use of intact sensing structures is advantageous in that both the transduction and conduction functions are contained in the native environment of the neural element. This novel approach is illustrated with antennule structures of the blue crab and characterized in terms of analytical responses to some amino acids.

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Biosensoren auf der Grundlage nativer Chemorezeptoren

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 75th birthday     

Where is analysis of trace elements in biotic matrices going to?

Summary Accomplishing the act of balancing our technological progress with the accompanying risks for safety and health in our life quality, calls for modern analytical science. It should serve as an indicator for the correct balance of forces in the substantial sphere. However, today such an indicating role is based on rough estimations, or on insufficient or unconfirmed information with respect to concentrations, binding forms and local distributions of toxic or of essential substances within a sample. Moreover, many complex mechanisms of synergetic and antagonistic physiological interactions have not yet been clarified — and consequently, we have to take into account severe misjudgements of risks.In addition, one has reached the limits of financial means required for the increasing control and survey tasks of daily analytical routine. Accordingly, only a long-term planned strategy for the development of more powerful, more reliable and more economic analytical methods, which moreover guarantee a better local distribution (microdistribution analysis), are the prerequisites for an improvement of this situation in analytical sciences.In view of the future tasks and the ultimate limits of trace- and micro-distribution analysis of the elements, the present state and an outlook on reaching the limit of analysis are critically discussed. Main emphasis is placed here on the possibility of improving conventional determination methods such as AAS, OES, XRFA, MS, NAA with regard to better power of detection and reliability. But also innovative analytical principles such as laser atomic spectroscopy (RIS, LEI, LIF) are introducted. They promise to develop into an essential basis for micro and trace element analysis of tomorrow.As instrumental methods are always the last step in an analytical procedure, a brief reference will be made to the problem of sample preparation, mainly with regard to the sources of systematic errors. As for trace analysis at the ng/ ml- or pg/ml-levels there are no reliable or certified standard reference materials available up to now, multistep procedures are still necessary. They must combine decomposition, preconcentration and determination methods in an optimal way to minimize systematic errors. The state-of-the-art of such multistep procedures in extreme elemental trace analysis will also be presented.

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über die zukünftige Entwicklung der Spurenelementanalyse in biotischen Matrices

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Dedicated to Prof. Dr. W. Fresenius in gratitude on the occasion of his 75th birthday.