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     

Determination of N-pesticides in natural waters

Summary Using RP-C18 material in cartridges to preconcentrate natural water samples, a number of important GC-detectable nitrogen containing pesticides can be analysed. This should be a first step to a simple monitoring of these water constituents for which a routine survey proved to be obligate in the near future.

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Bestimmung von N-Pesticiden in natürlichen Wasserproben

     

Mixed diet reference materials for nutrient analysis of foods: Preparation of SRM-1548 Total Diet

Summary Several mixed component diet materials have been available for use as reference materials for determination of elemental contents in food. These included H-9, issued by the IAEA and RM-8431, issued by NIST. Wide acceptance of these materials has exhausted supplies and they are no longer available. A new mixed food Standard Reference Material, SRM-1548 Total Diet, has been prepared and characterized for a number of elemental and organic constituents. This material was prepared from foods obtained from collections of the US FDA's Total Diet Study, which are representative of foods consumed by the US population. SRM-1548 has been composited from these foods, in proportions that are representative of daily intake. The composited foods were blended, freeze-dried, reblended and bottled in portions of 6 g. Homogeneity studies were carried out along with certification analyses for elements, cholesterol proximate and caloric content. This material is available from NIST and will be useful as a multi-purpose SRM for determinations of constituents in the naturally occurring range in foods and food related materials. Since this is a mixture of foods of both good and poorer sources, levels will be at the lower end of the concentration range for any individual constituent. Availability of further SRM's of individual foods with higher levels of specific constituents, such as SRM-1845 Cholesterol in Whole Egg will be required to extend the range of certified concentration values for food reference materials.     

Natural radioactivity and radiation hazards in some building materials used in Isparta,Turkey

The activity concentrations of uranium, thorium and potassium can vary from material to material and it should be measured as the radiation is hazardous for human health. Thus first studies have been planned to obtain radioactivity of building material used in the Isparta region of Turkey. The radioactivity of some building materials used in this region has been measured using a γ-ray spectrometry, which contains a NaI(Tl) detector connected to MCA. The specific activity for ²²⁶Ra, ²³²Th and ⁴⁰K, from the selected building materials, were in the range 17.91–58.88, 6.77–19.49 and 65.72–248.76 Bq/kg, respectively. Absorbed dose rate in air (D), annual effective dose (AED), radium equivalent activities (Ra_eq), and external hazard index (H_ex) associated with the natural radionuclide are calculated to assess the radiation hazard of the natural radioactivity in the building materials. It was found that none of the results exceeds the recommended limit value.     

Biological reference materials and analysis of toxic elements

Summary Biological monitoring of toxic metal pollution in the environment requires quality control analysis with use of standard reference materials. A variety of biological tissues are increasingly used for analysis of element bioaccumulation, but the available Certified Reference Materials (CRMs) are insufficient. An attempt is made to review the studies made using biological reference materials for animal and human tissues. The need to have inter-laboratory studies and CRM in the field of biological monitoring of toxic metals is also discussed.

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Biologische Referenzmaterialien und Analyse toxischer Elemente

     

Minimizing material damage using low temperature irradiation

Scientific advancements in healthcare driven both by technological breakthroughs and an aging and increasingly obese population have lead to a changing medical device market. Complex products and devices are being developed to meet the demands of leading edge medical procedures.Specialized materials in these medical devices, including pharmaceuticals and biologics as well as exotic polymers present a challenge for radiation sterilization as many of these components cannot withstand conventional irradiation methods. The irradiation of materials at dry ice temperatures has emerged as a technique that can be used to decrease the radiation sensitivity of materials.The purpose of this study is to examine the effect of low temperature irradiation on a variety of polymer materials, and over a range of temperatures from 0 °C down to ?80 °C. The effectiveness of microbial kill is also investigated under each of these conditions.The results of the study show that the effect of low temperature irradiation is material dependent and can alter the balance between crosslinking and chain scission of the polymer. Low temperatures also increase the dose required to achieve an equivalent microbiological kill, therefore dose setting exercises must be performed under the environmental conditions of use.     

Reference materials for chemical analysis. Highlights on the activity of JRC-Ispra laboratories

Summary Within the framework of a program of the Community Bureau of Reference concerning the preparation of compositional reference materials, examples are given of the activities of the Chemistry Division of the Joint Research Centre — Ispra Establishment, relating to the homogeneity verification, the analytical characterization and the derivation of consensus values of various constituents of different reference materials.

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Referenzmaterialien für die chemische Analyse. Besondere Aktivitäten der JRC-Laboratorien, Ispra

Zusammenfassung Beispiele werden gegeben zu den Aktivitäten der chemischen Abteilung des Forschungszentrums Ispra, die im Rahmen eines Programms des Europäischen Büros für Referenzmaterialien Arbeiten zur Herstellung solcher zusammengesetzter Materialien durchführt. Diese beziehen sich auf die Homogenitätsprüfung, sowie die analytische Charakterisierung und Ableitung des maßgebenden Wertes für verschiedene Bestandteile unterschiedlicher Referenzmaterialien.

Presented at Euroanalysis III conference, Dublin, 20–25 August, 1978     

Some new reference materials for organic elemental analysis: Their development and certification within the B. C. R. -Programme

Summary The procedure of manufacturing and certification of new reference materials intended to be used in organic elemental analysis is presented. The experience gained in the development of several materials has been used to design this procedure. A discussion of the requirements to be posed to a reference material in this field underlies the procedure. The results for five materials and the various methods used to obtain these results are given.

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Über einige Referenzmaterialien für die organische Elementaranalyse: deren Entwicklung und Certifizierung im Programm des B. C. R.

Zusammenfassung Die Arbeitsweise zur Entwicklung und Certifizierung neuer Referenzmaterialien für die organische Elementaranalyse wird angegeben. Zur Festlegung dieser Arbeitsweise wurde die Erfahrung bei der Entwicklung von mehreren Materialien angewendet. Das Verfahren gründet sich auf eine Diskussion der Anforderungen, die man an ein Referenzmaterial stellen muß. Die Ergebnisse von fünf Materialien sowie die verschiedenen Analysenmethoden, die zu diesen Ergebnissen führten, wurden angegeben.

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B. C. R.: Community Bureau of Reference; Commission of the European Community.     

The freeze-drying of orange juice for the preparation of reference materials

Summary The possibility of producing fruit juice reference materials is conditioned by the availability of a method which allows the transformation of the original juice or concentrate into a better physically stable form. Therefore a feasibility study of the transformation of orange juice by freeze-drying was carried out. In general, the obtained powder is hygroscopic, and tends to agglomerate into large solid lumps. Under optimal conditions of freeze-drying combined with redrying of the powder before closing the bottles, a slightly cohesive but physically stable yellow orange powder can however be obtained. Compared to the original juice, this shows no loss of reducing sugars and has a normal glucose-fructose ratio. Moreover, most aminoacids e.g. asparagine, methionine, lysine and arginine are not affected by freeze-drying. Based on the study of a limited number of important fruit juice parameters, it may be concluded that freeze-drying seems very promising in order to obtain an orange juice reference material, which after redissolution in water keeps the original chemical orange juice properties.

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Gefriertrocknung von Orangensaft für die Herstellung von Referenzmaterialien

     

Self-assembly of graphene oxide nanosheets in t-butanol/water medium under gamma-ray radiation

Graphene oxide (GO) nanosheets dispersed in strong acidic t-butanol/water medium can be reduced and self-assembled into a self-standing graphene hydrogel under γ-ray radiation, providing a facile and economical preparation method for hydroxylalkylated graphene-based aerogel.     

Development of a certified reference material for the content of nitroimidazole parent drugs and hydroxy metabolites in pork meat

Nitroimidazoles have been applied in the past to poultry and pigs to treat protozoan diseases and to combat bacterial infections, but due to adverse health effects their use in food-producing animals has meanwhile been banned in the EU. The request for a certified reference material in a representative matrix was stipulated by the responsible Community Reference Laboratory and is underpinned by the need to improve the accuracy and comparability of measurement data and to establish metrological traceability of analytical results. The Institute for Reference Materials and Measurements (IRMM) has responded to this demand by developing and producing a new certified matrix reference material, ERM-BB124. This incurred lyophilised pork meat material was certified according to ISO guides 34 and 35 for the mass fractions of six nitroimidazole compounds. Processing of the frozen muscle tissue to the final material was accomplished by application of cutting, freeze-drying, mixing and milling techniques. Homogeneity and stability measurements were performed using liquid chromatography tandem mass spectrometry. The relative standard uncertainty due to possible heterogeneity showed to be below 1.8% for all analytes. Potential degradation during transport and storage was assessed by isochronous stability studies. No significant instability was detected at a storage temperature of −20 °C for a shelf-life of 2 years. The certified mass fraction values were assigned upon evaluation of the data acquired in an international laboratory inter-comparison involving 12 expert laboratories using different sample preparation procedures, but exclusively LC-MS/MS methods. Relative standard uncertainty contributions for the characterisation (between-lab variation of mean values) were found to be between 1.6 and 4.8%. Certified values for five analytes were in the range of 0.7 to 6.2 μg kg⁻¹, with expanded relative uncertainties ranging between 7 and 14%. Dimetridazole could be certified as “<0.25 μg kg⁻¹ with a probability of 95%”. All values are traceable to the International System of Units (SI). The material is intended to be used for method validation purposes (including trueness estimation) and for method performance assessment.     

Application of independent methods and standard materials: An effective approach to reliable trace and ultratrace analysis of metals and metalloids in environmental and biological matrices

Summary Reliable trace analysis is only possible, if during methodological development independent analytical procedures or working standards and Standard Reference Materials are applied. Since at present only a few appropriate Standard Reference Materials are available, the existing gap has to be filled with e.g. working standards. Besides the application of independent methods, also as laboratory intercomparisons, for the determination of Pb, Cd, Cu, Ni and Hg in natural waters, sea water, urine, whole blood, marine organisms and wine, the current use of the NBS Standard Reference Materials Bovine Liver and Orchard Leaves is described. Further data are given of long term storage studies with blood samples and results of trace metal determinations in two working standards, fish muscle homogenate and algae, and in tentative future Standard Reference Materials (dried whole blood, blood plasma, phytoplankton, human hair, two aquatic and a terrestrial plant material).

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Anwendung unabhängiger Methoden und Standardmaterialien: Ein Weg zur zuverlässigen Spuren- und Ultraspurenanalyse von Metallen und Metalloiden in Umwelt- und biologischen Matrices

Zusammenfassung Zuverlässige Spurenanalyse ist nur möglich, wenn während der methodischen Entwicklung entweder unabhängige Verfahren eingesetzt oder Arbeitsstandards, bzw. Standard-Referenz-Materialien verwendet werden. Da gegenwärtig nur einige wenige geeignete Standard-Referenz-Materialien verfügbar sind, muß die bestehende Lücke u.a. mit Arbeitsstandards geschlossen werden. Neben der Anwendung unabhängiger Methoden, auch als externer Methodenvergleich, zur Bestimmung von Pb, Cd, Cu, Ni und Hg in Süß- und Meerwasser, Harn, Vollblut, marinen Organismen und Weinen wird die laufende Anwendung der NBS Standard-Referenzmaterialien Bovine Liver und Orchard Leaves beschrieben. Weiter werden Daten von Langzeitstudien mit Blutproben sowie die Ergebnisse der Bestimmungen von Spurenmetallgehalten in den Arbeitsstandards Fischmuskel-homogenat und Algen sowie in Entwicklung befindlichen Standard-Referenzmaterialien (Trockenvollblut, Blutplasma, Phytoplankton, menschliches Haar sowie zwei aquatischen und einer terrestrischen Pflanze) mitgeteilt.

Presented at Euroanalysis III conference, Dublin, August 20–25, 1978     

Radiation treatment for sterilization of packaging materials

Treatment with gamma and electron radiation is becoming a common process for the sterilization of packages, mostly made of natural or synthetic plastics, used in the aseptic processing of foods and pharmaceuticals. The effect of irradiation on these materials is crucial for packaging engineering to understand the effects of these new treatments. Packaging material may be irradiated either prior to or after filling. The irradiation prior to filling is usually chosen for dairy products, processed food, beverages, pharmaceutical, and medical device industries in the United States, Europe, and Canada. Radiation effects on packaging material properties still need further investigation. This paper summarizes the work done by different groups and discusses recent developments in regulations and testing procedures in the field of packaging technology.     

Preparation and certification of JAC river water reference material for trace element analysis

 The Japan Society for Analytical Chemistry has recently issued a river water-certified reference material (CRM) for use in the ultratrace analysis of elements in fresh water. The river water CRM consists of a set of two (natural and spiked) 500-ml samples. The natural water is certified for Pb, Cr, As, Cu, Fe, Mn, Zn, B and Al at their sub-μg/l levels, while the spiked water is intended for use in the regulatory analysis of tap water and fresh water. Key words River water · Trace element analysis · Regulatory analysis · Reference materials     

Reference materials for agricultural and food analysis: Preparation and physical characterization of a bovine muscle powder candidate reference material

Summary The most cost-effective way of monitoring and maintaining reliability of an analytical procedure 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 both the sought-for analyte and the remainder of the supporting material (matrix) which are not reflected in currently-available biological reference materials (BRMs). In an attempt to fill some of these gaps in the world repertoire of reference materials, cooperative work is underway to prepare and characterize a number of materials for data quality control for inorganic constituents. The first two products of this venture, Maize Stalk and Maize Kernel Reference Materials 8412 and 8413, respectively, with recommended concentrations for eleven elements are available from USNBS. A third product, a powdered Bovine Muscle candidate reference material has been prepared in quantity. Meat from beef cattle (Bos Taurus) comprising muscles commonly-denoted round steak was trimmed, ground, freeze-dried, -ray sterilized, ball milled, sieved, blended and packaged. The final product was a finely powdered, visually uniform material consisting of muscle fibers with over 70% of the particles with radius of an equivalent sphere in the range 10–40 m (median 25 m).Efforts are underway to develop a number of other BRMs representative of the large number of important food classes. Cooperative work with expert analytical laboratories is anticipated to lead to characterization of the Bovine Muscle candidate reference material and the other materials in respect of concentrations of a large number of nutritionally, toxicologically and environmentally-important major, minor and trace chemical elements as well as proximate constituents such as protein, fibre, fat and ash.Contribution No. 86-68 from Land Resource Research Centre     

Water molecule-induced hydrogen bonding between cellulose nanofibers toward highly strong and tough materials from wood aerogel

Lightweight, highly strong and bio-based structural materials remain a long-lasting challenge. Here, inspired by nacre, a lightweight and high mechanical performance cellulosic material was fabricated via a facile and effective top-down approach and the resulting material has a high tensile strength of 149.21 MPa and toughness of 1.91 MJ/m³. More specifically, the natural balsawood (NW) was subjected to a simple chemical treatment, removing most lignin and partial hemicellulose, follow by freeze-drying, forming wood aerogel (WA). The delignification process produced many pores and exposed numerous aligned cellulose nanofibers. Afterwards, the WA absorbed a quantity of moisture and was directly densified to form above high-performance cellulosic material. Such treatment imitates highly ordered “brick-and-mortar” arrangement of nacre, in which water molecules plays the role of mortar and cellulose nanofibrils make the brick part. The lightweight and good mechanical properties make this material promising for new energy car, aerospace, etc. This paper also explains the strengthening mechanism for making biomimetic materials by water molecules-induced hydrogen bonding and will open a new path for designing high-performance bio-based structural materials.     

Surface cleaning techniques: ultra-trace ICP-MS sample preparation and assay of HDPE

The world’s most sensitive radiation detection and assay systems depend upon ultra-low-background (ULB) materials to reduce unwanted radiological backgrounds. In this study, we evaluate methods to clean HDPE, a material of interest to ULB systems and the means to provide rapid assay of surface and bulk contamination. ULB-level material and ultra-trace-level detection of actinide elements is difficult to attain, due to the introduction of contamination from sample preparation equipment such as pipette tips, sample vials, forceps, etc and airborne particulate. To date, literature available on the cleaning of such polymeric materials and equipment for ULB applications and ultra-trace analyses is limited. For these reasons, a study has been performed to identify an effective way to remove surface contamination from polymers in an effort to provide improved instrumental detection limits. Inductively Coupled Plasma Mass Spectroscopy was utilized to assess the effectiveness of a variety of leachate solutions for removal of inorganic uranium and thorium surface contamination from polymers, specifically high density polyethylene (HDPE). Leaching procedures for HDPE were tested to optimize contaminant removal of thorium and uranium. Calibration curves for thorium and uranium ranged from 15 ppq (fg/mL) to 1 ppt (pg/mL). Detection limits were calculated at 6 ppq for uranium and 7 ppq for thorium. Results showed the most effective leaching reagent to be clean 6 M nitric acid for 72 h exposures. Contamination levels for uranium and thorium found in the leachate solutions were significant for ultra-low-level radiation detection applications.     

BCR edible oils and fats reference materials

Summary The Community Bureau of Reference (BCR) has recently made available three certified reference materials (CRM's) viz. a soya-bean oil/maize germ oil blend, a beef fat/pig fat blend, and an anhydrous milk fat (butterfat) with added vanillin and phytosterols. The results from inter-laboratory studies designed to obtain certified and indicative values for specific properties of the materials are reviewed and the application of the CRM's in quality assurance and method validation/standardisation described.

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BCR-Referenzmaterialien für Speiseöle und -fette

     

Preparation and value assignment of standard reference material 968e fat-soluble vitamins, carotenoids, and cholesterol in human serum

Standard Reference Material 968e Fat-Soluble Vitamins, Carotenoids, and Cholesterol in Human Serum provides certified values for total retinol, γ- and α-tocopherol, total lutein, total zeaxanthin, total β-cryptoxanthin, total β-carotene, 25-hydroxyvitamin D₃, and cholesterol. Reference and information values are also reported for nine additional compounds including total α-cryptoxanthin, trans- and total lycopene, total α-carotene, trans-β-carotene, and coenzyme Q₁₀. The certified values for the fat-soluble vitamins and carotenoids in SRM 968e were based on the agreement of results from the means of two liquid chromatographic methods used at the National Institute of Standards and Technology (NIST) and from the median of results of an interlaboratory comparison exercise among institutions that participate in the NIST Micronutrients Measurement Quality Assurance Program. The assigned values for cholesterol and 25-hydroxyvitamin D₃ in the SRM are the means of results obtained using the NIST reference method based upon gas chromatography-isotope dilution mass spectrometry and liquid chromatography-isotope dilution tandem mass spectrometry, respectively. SRM 968e is currently one of two available health-related NIST reference materials with concentration values assigned for selected fat-soluble vitamins, carotenoids, and cholesterol in human serum matrix. This SRM is used extensively by laboratories worldwide primarily to validate methods for determining these analytes in human serum and plasma and for assigning values to in-house control materials. The value assignment of the analytes in this SRM will help support measurement accuracy and traceability for laboratories performing health-related measurements in the clinical and nutritional communities.