Survey of selected materials for use as an organic nutrient standard

Summary There is a need for food based reference materials characterized for organic nutrient content, since very few are presently available. A series of twelve food matrices has been prepared by Agriculture Canada as Candidate Reference Materials. This paper reports a survey of the organic nutrient content of these twelve materials which include bovine muscle powder, corn starch, hard red spring wheat flour, soft winter wheat flour, white granulated sugar, whole milk powder, wheat gluten, potato starch, corn bran, durum wheat flour, whole egg powder, and microcrystalline cellulose. Whole egg, bovine muscle and whole milk powder appear to be best suited for further development as organic nutrient standards.

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Überblick über ausgewählte Materialien zur Verwendung als Standards für organische Nährstoffe

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Contribution Number 88-65 from Land Resource Research Center     

Summary of preparation and homogeneity characterization of ten agricultural food reference materials for elemental composition

Summary Preparation and development has been completed of ten agricultural/food reference materials (RMs): bovine muscle powder, corn starch, hard red spring wheat flour, soft winter wheat flour, whole milk powder, wheat gluten, corn bran, durum wheat flour, whole egg powder and microcrystalline cellulose. Homogeneity tests for 14 elements, Al, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were performed by the initiating laboratories by application of precise and reliable analytical methods based on flame atomic absorption spectrometry and graphite furnace atomic absorption spectrometry. An extensive set of analytical results obtained from the interlaboratory cooperative characterization campaign was assessed to provide homogeneity estimates for other elements. Estimates of homogeneity from within-laboratory precision indicated that all materials exhibited acceptable homogeneity for virtually all 29 elements (Al, As, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Se, Sr, V, Zn) for which best estimate concentration values are available. Two thirds of all homogeneity coefficients of variation were below 5%.     

Preparation and homogeneity characterization of ten agricultural/food reference materials for elemental composition

Summary Ten agricultural/food reference materials (RM): bovine muscle powder, corn starch, hard red spring wheat flour, soft winter wheat flour, whole milk powder, wheat gluten, corn bran, Durum wheat flour, whole egg powder and microcystalline cellulose, were prepared by milling, irradiation, sieving, blending and packaging procedures. Homogeneity tests for 14 elements in randomly selected units were performed by the initiating laboratories by application of various analytical methods. Al, Ca, Cu, Fe, K, Mg, Mn, Na, Sr and Zn were determined by acid digestion flame atomic absorption spectrometry, and Cd, Co, Ni and Pb using acid digestion graphite furnace atomic absorption spectrometry after separation/preconcentration of the analytes by co-precipitation. In addition, the extensive set of analytical results obtained from the interlaboratory cooperative characterization campaign was assessed to provide homogeneity estimates for other elements. Measures of homogeneity were estimated from the within-laboratory precision from the more precise laboratories. All materials exhibited acceptable homogeneity for virtually all 29 elements (Al, As, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Se, Sr, V, Zn) for which best estimate concentration values were available, an essential pre-requisite in establishing reference values for these materials. Sixty-two percent of all homogeneity coefficients of variation (CV) were below 5%, with Br, Ca, Cl, Mg, Na, P, Zn and especially K and N exhibiting very high homogeneity CV less than 1% in some cases.Contribution no. 92–148 from Centre for Land and Biological Resources Research     

Preliminary assessment of homogeneity of new candidate agricultural/food reference materials

Summary In an effort to bring to the analytical community new natural matrix reference materials (RM's) for elemental composition quality control, ten new agricultural/food candidate reference materials prepared previously, were characterized for homogeneity. The materials include bovine muscle powder, whole egg powder, corn bran, microcrystalline cellulose, wheat gluten, whole milk powder, corn starch and three wheat flours representing a wide range of matrix types and elemental composition. Characterization was for up to some twenty five major, minor, trace and ultratrace elements of nutritional, toxicological and environmental significance. Solid sampling electrothermal atomic absorption spectrometry was applied to the determination of copper and lead in sub-milligram subsamples. A variety of other analytical techniques via an interlaboratory cooperative effort was used to determine many other elements in 100–2000 mg subsample sizes. Good material homogeneity was observed for virtually all materials and analytes with the exception of Cr and Pb in limited instances. The materials were thus deemed suitable for detailed characterization of elemental concentration to lead to recommended values and to bring these biological products to reference material status.     

Homogeneity studies in reference materials with Zeeman solid sampling GFAAS

Summary The homogeneity of lead and cadmium in reference materials was investigated by solid sampling GFAAS. The following materials were comparatively analyzed: Standard reference materials from NBS, Washington 1567 Wheat flour, 1568 Rice flour and 1577a Bovine liver, certified reference materials from BCR, Brussels, No 63 Milk powder, No 184 Bovine muscle, No 185 Bovine liver, No 186 Pig kidney, No 189 Wholemeal flour, No 191 Brown bread and a whole fish (dab) homogenate from the environmental specimen bank in the FRG. The results are remarkably different for the investigated materials.

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Homogenit?tsstudien in Referenzmaterialen mit Zeeman-Feststoff-GFAAS

     

Development of food reference materials for nutritional analysis

Summary The development of five reference materials for major nutritional properties, whole milk powder, pork muscle, wheat and rye flour, and haricots verts beans is described. Homogeneity and stability of these materials proved to be adequate. A preliminary intercomparison of methods showed that results for total fat and total dietary fibre were method dependent. Evaluation of methods used for available carbohydrates revealed poor solubilisation and hydrolysis of starch in some laboratories. This intercomparison has given valuable information for the final certification of these materials.     

同位素稀释-液相色谱-串联质谱法在小麦粉细交链孢菌酮酸和腾毒素标准物质制备和定值中的应用

建立了小麦粉中细交链孢菌酮酸（TeA）和腾毒素（TEN）标准物质的研制和定值方法,为开展粮食中交链孢霉毒素基体标准物质的研制提供重要方法学借鉴。该标准物质样品为天然污染交链孢霉毒素的小麦籽粒,定值目标物为TeA和TEN,采用同位素稀释-液相色谱-串联质谱法（ID-LC-MS/MS）进行定值测量,多个实验室合作定值。所研制的标准物质具有常温避光保存、定值不确定度小等特点。该标准物质是目前国际上唯一一种天然污染TeA和TEN的小麦粉标准物质,可用于食品安全风险监测、产品质量检测等领域相关分析方法的评价和测量质量控制等。     

Characterization (certification) of three wheat flours and a wheat gluten reference material (NIST RM 8436, 8437, 8438 and 8418) for essential and toxic major, minor and trace element constituents

Summary Three wheat flours, Durum Wheat Flour (NIST RM 8436), Hard Red Spring Wheat Flour (NIST RM 8437), Soft Winter Wheat Flour (NIST RM 8438) and Wheat Gluten (NIST RM 8418) Reference Materials were characterized for essential and toxic major, minor and trace elemental composition by analysts in an interlaboratory cooperative characterization campaign. Extensive application of widely varied analytical methods yielded 16–27 best estimate and 3–8 informational concentration values for each of these materials. These reference materials are intended for analytical quality control of element determinations in flour and flour products as well as other agricultural/food materials with related matrices.Contribution No. 92–145 from Centre for Land and Biological Resources Research     

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 certification of major components and major elements in five food reference materials

Summary The development of five food reference materials (whole milk powder, pork muscle, rye and wheat flour, and haricot beans) is described. Homogeneity and stability of three categories of nutrients, major components, major elements and vitamins, proved to be adequate. Certification of Kjeldahl nitrogen, total fat, lactose, total dietary fibre (AOAC method), ash, Na, K, Mg, Ca, and Cl contents was successful. In contrast, only indicative values could be given for starch and sugars, nonstarch polysaccharides and P because of insufficient agreement between laboratories. The measurement of these components and elements need further study to obtain the improvement needed. Indicative values for retinol, -carotene, -tocopherol, vitamin B₁, vitamin C, and niacin in some of these materials could be given. Prospects for future certification of vitamins are favourable.     

Principe,possibilites et applications de l'analyse par activation aux photons gamma

The various photonuclear reactions suitable for analytical purposes, their specificity and their performances are reviewed. The influence of the experimental irradiation conditions on the theoretical detection limits permitted and on the relative importance of competitive nuclear reactions liable to interfere is examined, with special reference to the determination of carbon, nitrogen and oxygen. It is shown that these parasitic effects of nuclear origin may be eliminated by the choice of the maximum irradiation energy. Examples are given of applications relative to trace determinations of lights elements, especially carbon, nitrogen, and oxygen, in metals or semi-conductors and to instrumental multi-element analyses of biological materials, atmospheric sampling filters and above all agricultural products.

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Conférence plénière prononcée dans le cadre du: 5th Symposium on the Recent Development in Activation Analysis, Oxford (GB), 17–21 Juillet 1978.     

Development of mycotoxin reference materials

Summary The analytical difficulties in mycotoxin determination have given rise to the development of mycotoxin reference materials by the European Community Bureau of Reference (BCR) in cooperation with several European Laboratories, among them the National Institute of Public Health and Environmental Protection. The first project undertaken concerned four milk powders certified for their aflatoxin M₁ content (concentrations 0, 0.1, 0.3 and 0.8 g/ kg). Projects that are well-advanced include two peanut meals (aflatoxin B₁ contents 0 and ca. 200 g/kg) and two compounded animal feedingstuffs (aflatoxin B₁ contents 0 and 10 g/kg). Mycotoxin reference materials are also under development for zearalenone in wheat and maize, and for ochratoxin A in wheat.The general approach followed in the development and certification of mycotoxin reference materials (preparation, testing for homogeneity and stability, intercomparisons of methods and certification exercise) will be discussed and exemplified with the help of the completed project on aflatoxin M₁ in milk powder.

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Entwicklung von Mycotoxin-Referenzmaterialien

     

Protein immunoassay methods for detection of biotech crops: applications,limitations, and practical considerations

Immunoassay methods are available for detection and quantitation of proteins expressed by most biotechnology-derived crops in commercial production. The 2 most common test formats are enzyme-linked immunosorbent assay (ELISA) and immunochromatographic (lateral flow) strip tests. Two ELISA methods, one for Roundup Ready soybeans and one for MON810 CrylAb corn, were the subject of large international collaborative studies and were demonstrated to quantitatively determine the concentrations of biotech crops in samples of ground grain. Quantitative ELISA methods are also useful for analysis of processed fractions of agricultural commodities such as soybean toasted meal or corn flour. Both strip tests and ELISAs for biotech crops are currently being used on a large scale in the United States to manage the sale and distribution of grain. In these applications, tests are used to determine if the concentration of biotech grain is above or below specified threshold limits. Using existing U.S. Department of Agriculture sampling techniques, the reliability of the threshold determination is expressed in terms of statistical confidence rather than analytical precision. Combining the use of protein immunoassays with Identity Preservation systems provides an effective means of characterizing the raw and processed agricultural inputs to the food production system in a way that allows food producers to comply with labeling laws.     

Criteria for the development of biological reference materials

Summary A review is presented of factors to be considered in the development of biological reference materials. Some guidelines are offered regarding approaches to the generation of the varied materials required for analytical quality control. Major considerations in such an endeavour are the goal of the undertaking and role of the final product, selection of candidate materials, preparation, characterization and certification. Selection of materials should be from those important to commerce and consumers, and related to various regulatory, clinical, environmental, and research activities. They should adequately represent the different choices and types of foodstuffs, clinical materials and environmental materials, such as soils, sewage sludges, plant and animal tissues, of interest in different regions of the world.Acquisition can be from commercial sources or the result of in-house preparation, with attention to stability enhancement if required and maintenance of native analyte levels by minimization of contamination. The approach to chemical and physical characterization relies on the measurement philosophy, selection of analytes, their speciation, and selection of analytical methods and analysts for establishment of homogeneity and quantitative levels. Throughout the overall task of RM development there is a requirement for a critical approach by critical analytical and measurement scientists and the involvement of national RM agencies in order to produce top quality control materials.

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Kriterien für die Entwicklung von biologischen Referenzmaterialien

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Contribution No. 88-50 from Land Resource Research Centre     

Biodegradation study of plasticised corn flour/poly(butylene succinate-co-butylene adipate) blends

Plasticised corn flour/poly(butylene succinate-co-butylene adipate) (PBSA) materials were prepared by extrusion and injection in order to study the impact of PBSA ratio on their physicochemical properties and biodegradability. Scanning electron microscopy observations showed that corn flour and PBSA are incompatible. Three types of morphology have been observed: (i) starch dispersed in a PBSA matrix, (ii) a “co-continuous-like” morphology of starch and PBSA, and (iii) PBSA dispersed in a starch matrix. As expected, the extent of plasticised corn flour starch hydrolysis by amylolytic enzymes decreased when the amount of PBSA increased. Addition of a lipase to hydrolyse PBSA ester bonds enhanced enzymatic hydrolysis of starch by amylolytic enzymes in materials where PBSA formed a continuous phase. This suggests that PBSA formed a barrier restricting the access of amylolytic enzymes to starch. This was consistent with aerobic and anaerobic biodegradation assays, which also showed lower biodegradability of materials containing a majority of PBSA.     

Analytische Aspekte der Oxydation organischer Stickstoffverbindungen mit Chromsäure. XXI

Zusammenfassung Die gleichzeitige Bestimmung von C-Methyl- und Stickstoffgruppen mit Chrom—Schwefelsäure wurde auf Derivate der Carbonylverbindungen erweitert. Während die Analysenergebnisse für stickstoffhaltige Gruppen durchwegs der Theorie entsprachen, sank die Essigsäureausbeute aus den Aldehydderivaten mit der Kettenlänge und war allgemein größer als aus den Ketonderivaten mit derselben Zahl an Kohlenstoffatomen. Die Resultate waren insgesamt gut reproduzierbar. Sie wurden hinsichtlich der Struktur der untersuchten Substanzen diskutiert.

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Analytical aspects of the oxidation of organic nitrogen compounds with chromic acid. XXI

Summary The simultaneous determination of C-methyl- and nitrogen groups with chromic-sulfuric acid was extended to derivatives of the carbonyl compounds. Although the analytical results invariably agreed with theory insofar as groups containing nitrogen were concerned, the yield of acetic acid from aldehyde derivatives sank as the chain length increased and in general was greater than the yield from ketone derivatives having the same number of carbon atoms. As a whole, the results were satisfactorily reproducible. They are discussed with respect to the structure of the substances investigated.

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XX. Mitteilung, s. 1.

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In dieser Mitteilung ist der dritte (letzte) Teil der Dissertationsarbeit von Frau Dipl.-Ing.J. Kalousovd einbegriffen.     

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.

     

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)