Standards biological materials

National Institute of Standards and Technology (NIST). The NIST is the source of many of the standards used in chemical and physical analyses in the United States and throughout the world. The standards prepared and distributed by the NIST are used to caUbrate measurement systems and to provide a central basis for uniformity and accuracy of measurement. At present, over 1200 Standard Reference Materials (SRMs) are available and are described by the NIST (15). Included are many steels, nonferrous alloys, high purity metals, primary standards for use in volumetric analysis, microchemical standards, clinical laboratory standards, biological material certified for trace elements, environmental standards, trace element standards, ion-activity standards (for pH and ion-selective electrodes), freezing and melting point standards, colorimetry standards, optical standards, radioactivity standards, particle-size standards, and density standards. Certificates are issued with the standard reference materials showing values for the parameters that have been determined. 

Bowen HJM (1965) A standard biological material for elementary analysis. In Shallis PW, ed. Proc of the SAC Conference, Nottingham, pp 25-31. W Heifer and Sons, Cambridge. 

It is advisable to include in the sample run standard materials of a type similar to the samples being examined. Standard biological materials and river sediments are available from the National Bureau of Standards USA. 

NAA is a quantitative method. Quantification can be performed by comparison to standards or by computation from basic principles (parametric analysis). A certified reference material specifically for trace impurities in silicon is not currently available. Since neutron and y rays are penetrating radiations (free from absorption problems, such as those found in X-ray fluorescence), matrix matching between the sample and the comparator standard is not critical. Biological trace impurities standards (e.g., the National Institute of Standards and Technology Standard Rference Material, SRM 1572 Citrus Leaves) can be used as reference materials. For the parametric analysis many instrumental fiictors, such as the neutron flux density and the efficiency of the detector, must be well known. The activation equation can be used to determine concentrations ... 

Tu Shu-Db, Lieser KH (1984) Homogeneity test of Chinese biological standard reference materials by means of instrumental neutron activation analysis, f Radioanal Nucl Chem Articles 84 301-306. 

De Goeij JJM, VorKERS KJ, Tjioe PS, and Kroon JJ (1978) NBS SRM 1569 Brewer s yeast Is it an adequate standard reference material for testing chromium determination in biological materials. Radiochem Radioanal Letters 35 139-146. 

Gladney ES (1980) Elemental concentrations in NBS biological materials and environmental standard reference materials. Anal Chim Acta 118 385-396. 

Gladney ES, O Malley BT, Roeiandts I, and Gills TE (1987,1993 update) Standard Reference Materials Compilation of Elemental Concentration Data for NBS Chemical, Biological Geological and Environmental SRMs. NBS Spec Pub 260-111, NIST, Gaithersburg, MD. 

It is largely without debate that the term "reference substance" includes those chemical and biological materials that are used as standards in a study (i.e., those materials used for response comparison purposes, such as analytical reference standards). Normally, one thinks of reference substances as just referring to specimen (sometimes referred to as "matrix samples") analyses, but the characterization of test, control, and reference substances (see... 

The nomenclature of nickel compounds should be further standardized (WHO 1991). Analytical methods must be developed and standardized in order to facilitate speciation of nickel compounds in atmospheric emissions, biological materials, and in other environmental samples (NAS 1975 WHO 1991). Studies are needed to elucidate the biogeochemical nickel cycle on a global scale and determine its potential for long-range transport (WHO 1991). 

Two important, but often under emphasized, aspects of measuring c/w values and isotherms in foods are accuracy and repeatability. Variation in and isotherm values can be due to inherent variation in biological materials, as well as differences in measurement methods, protocols, and equipment employed. Wolf et al. (1985) presented the results of a COST 90 Project on the standardization of saturated salt solution isotherm measurement methodology and Lewicki and Pomaranska-Lazuka (2003) discussed errors in the static desiccator method. 

Since NMR is at present an emerging method for the characterization of mechanical waves, it cannot as yet be considered as a gold standard in elastography. In the same way the use of ultrasounds (US) for characterizing crystalline, amorphous or biological materials is also an emerging research... 

Reference substance (EPA only) Any chemical substance or mixture, or analytical standard, or material other than a test substance, feed, or water, that is administered to or used in analyzing the test system in the course of a study for the purposes of establishing a basis for comparison with the test substance for known chemical or biological measurements. 

Metabolites of 2-hexanone in biological materials are difficult to determine in routine practice because of the lack of standardized methods for their measurement. As shown in Table 6-1, there are very few well characterized methods for the determination of metabolites of 2-hexanone in biological materials (Nomeir and Abou-Donia 1985 White et al. 1979). The precision, accuracy, reliability, and specificity of existing methods need to be evaluated, and the methods refined and adapted to routine practice. 

Some of the methods commonly used for the determination of thorium in biological materials are given in Table 6-1. The colorimetric methods are not capable of isotope-specific determination of thorium isotopes. Alpha spectrometric and neutron activation analysis are useful in the quantification of isotope-specific thorium and thorium-232, respectively, and have better sensitivities than colorimetric methods. Alpha spectrometry is the commonly used isotope-specific analysis for the determination of thorium-232 and the thorium-230 derived from the decay of uranium-238 (Wrenn et al. 1981). Standard reference materials (SRMs) containing thorium in human liver (SRM-4352) and human lung (SRM-4351) necessary for the determination of absolute recovery in a given sample are available from the National Institute of Standards and Technology (Inn 1987). 

More research is needed on the accurate measurement of boron in biological materials when the concentrations are <1.0 mg B/kg (Sullivan and Culver 1998). Standard biological reference materials with low boron levels need to be produced for use in interlaboratory comparisons. This becomes especially important in studies on boron-deficiency states and the ability of the organism to conserve boron at very low intakes (Sullivan and Culver 1998). More research is needed on homeostatic regulation of boron and functional markers of boron metabolism (Sutherland et al. 1998). Sullivan and Culver (1998) recommend additional studies to establish ... 

Methods for Parent Compound and Metabolites in Biological Materials. No information is available concerning the analysis of isophorone in biological materials. If information were available, it would allow both investigators and reviewers to assess the accuracy and uncertainty of the methods used. Furthermore, the ready availability of tested analytical methods would permit a standardized approach to the analysis of biological materials and allow a comparison of the levels of exposure with the possible health effects in humans. 

An analytical procedure has been proposed for precise uranium isotope ratio measurements in a thin uranium layer on a biological surface by LA-ICP-MS using a cooled laser ablation chamber.125 One drop of uranium isotope standard reference materials NIST, 350, NIST 930, of our isotopic laboratory standard CCLU 500 (20p.l, U concentration 200 ng 1) and of uranium with natural isotopic pattern were deposited on the leaf surface and analyzed by LA-ICP-MS at well defined laser crater diameters of 10, 15, 25 and 50 p.m. A precision for measurements of isotope ratios in the range of 2.1-1.0% for 235U/238U in selected isotope standards was observed whereby the precision and the accuracy of isotope ratios compared to the non-cooled laser ablation chamber was improved.125... 

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