Trace element control

Schwartz, K., Milne, D.B. and Vinyard, E. (1970). Growth elfects of tin compounds in rats maintained in a trace element-controlled environment, Biochem. Biophys. Res. Comm., 40, 22-29. 

Th, Co, and, in some locations, Fe. Surfece-water enrichments are usually caused by rapid rates of supply to the mixed layer via atmospheric deposition or river runoff. Removal usually occurs through relatively rapid precipitation into or adsorption onto sinking particles. Trace elements controlled by scavenging tend to have short (100 to lOOOy) residence times. Since these residence times are less than the mixing time of the ocean, significant geographic gradients are common. 

Schwarz, K. Spallholz, J. Growth effects of small cadmium supplements in rats maintained under trace-element controlled conditions. Fed. Proc.. 1976, 255. 

Chemiluminescence has been studied extensively (2) for several reasons (/) chemiexcitation relates to fundamental molecular interactions and transformations and its study provides access to basic elements of reaction mechanisms and molecular properties (2) efficient chemiluminescence can provide an emergency or portable light source (J) chemiluminescence provides means to detect and measure trace elements and pollutants for environmental control, or clinically important substances (eg, metaboHtes, specific proteins, cancer markers, hormones, DNA) and (4) classification of the hioluminescent relationship between different organisms defines their biological relationship and pattern of evolution. 

Efficient homeostatic controls of mammalians generally prevent serious toxicity from ingestion of the mineral nutrients. Toxicity may occur under conditions far removed from those of nutritional significance or for individuals suffering from some pathological conditions. Because of very low concentrations in foods, the trace elements are not toxic under normal nutritional conditions. Exceptions are selenium and iron (162). 

Pha.rma.ceutica.1 Purity. A safety profile of a generic dmg can differ from that of the brand-name product because different impurities may be present in each of the dmgs (154). Impurities can arise out of the manufacturing processes and may be responsible for adverse interactions that can occur. Eor example, serious adverse reactions (LyeU syndrome) were observed upon the use of isoxicam in 1985. These seemed to have resulted from trace elements of a manufacturing by-product that was within the manufacturing quaUty control specifications. 

Trace elements which adversely affect intercrystalline attack are normally controlled at a safe level. Copper is particularly pertinent in this respect since relatively small additions can cause a marked increase in intercrystalline attack in some alloy systems (Sections 1.3 and 1.7). 

Typical applications of such methods are the determination of trace elements in (a) the investigation of pollution problems (b) the examination of geological specimens (c) quality control in the manufacture of semiconductors. 

The examples discussed above suggest useful directions for future research involving trace element analysis of bones. Specifically, the effects of developmental age and other factors (e.g., porosity, mineralization) that may lead to differences in surface area of specimens should be considered. Diage-netic effects should be monitored by analysis of a suite of elements whose abundances are not controlled by dietary abundances (e.g., Mn, Zr, etc.). Finally, although alkaline elements such as Sr and Ba are most likely to reflect the Sr/Ca and Ba/Ca levels of the diet, omnivores such as humans are likely to obtain the majority of these elements from plants rather than from animals. Therefore for accmate diet reconstruction it is necessary to determine the total abundance of Ca as and the Sr/Ca and Ba/Ca ratios of the plant and animal resources that were potential dietary staples. The effects of culinary practices on elemental abundances (Burton and Wright 1995 Katzenberg et al. this volume) must also be evaluated. 

A current area of interest is the use of AB cements as devices for the controlled release of biologically active species (Allen et al, 1984). AB cements can be formulated to be degradable and to release bioactive elements when placed in appropriate environments. These elements can be incorporated into the cement matrix as either the cation or the anion cement former. Special copper/cobalt phosphates/selenates have been prepared which, when placed as boluses in the rumens of cattle and sheep, have the ability to decompose and release the essential trace elements copper, cobalt and selenium in a sustained fashion over many months (Chapter 6). Although practical examples are confined to phosphate cements, others are known which are based on a variety of anions polyacrylate (Chapter 5), oxychlorides and oxysulphates (Chapter 7) and a variety of organic chelating anions (Chapter 9). The number of cements available for this purpose is very great. 

Here we might note that cobalt(II) hydroxide, but not the oxide, also forms cements (Allen et al., 1984 Mansion Gleed, 1985 Prosser et al., 1986). It also is used in controlled-release devices for supplying trace elements to cattle and sheep. Nothing is known of its structure. 

Benoit J, Gihnour CC, Heyes A, MasonRP, Miller C. 2003. Geochemical and biological controls over methyhnercury production and degradation in aquatic ecosystems. In Chai Y, Braids OC, editors. Biogeochemistry of environmentally important trace elements, ACS Symposium Series 835. Washington, D.C. American Chemical Society, p. 262-297. 

KuRFiiRST U, Grobecker KH, Stoeppler M (1984) Homogeneity studies in biological reference and control materials with solid sampling and direct Zeeman-AAS. In Schramel P, Bratter P, eds. Trace Element Analytical Chemistry in Medicine and Biology, Vol. 3, pp 591-601. de Gruyter, Berlin. 

Quevauviller Ph, Maier EA, Vercoutere K, Muntau H, Griepink B (1992a) Certified reference material (CRM 397) for the quality control of trace element analysis of human hair. Fresenius J Anal Chem 343 335-338. 

Quevauviller Ph, Herzig R. and Muntau H (1996b) Certified reference material of lichen (CRM 482) for the quality control of trace element biomonitoring. Sci Total Environ 187 143-152 Quevauviller Ph, Lachica M., Barahona E, Rauret G, Ure A, Gomez A, and Muntau H (1997) The certification of the EDTA-extractable contents (mass fractions) of Cd, Cr, Ni, Pb, and Zn and of the DTPA-extractable contents (mass fractions) of Cd and Ni in calcareous soil by the extraction procedures given CRM 600. EUR Report 17555 Quevauviller Ph. Maier EA, and Griepink B, eds. (1995) Quality Assurance for Environmental Analysis. Elsevier. Amsterdam. 

The literature includes a number of mis-matches, the following standing as examples for the many The use of bovine liver and other animal tissues for QC in the analysis of hmnan body fluids should not be considered by analysts. The matrix and the levels of trace elements do not match the levels to be analyzed, which may lead to serious errors. An even more severe mis-use was recently reported by Schuhma-cher et al. (1996) for NIST SRM 1577a Bovine Liver, which was used for QC in the analysis of trace elements in plant materials and soil samples in the vicinity of a municipal waste incinerator. Also recently, Cheung and Wong (1997) described how the quality control for the analysis of trace elements in clams (shellfish) and sediments was performed with the same material NIST SRM 1646, Estuarine sediment. Whilst the selected SRM was appropriate for sediments, its usefulness as a QC tool for clams is difficult to prove see also Chapter 8. This inappropriate use is the more mystifying because a broad selection of suitable shellfish RMs from various producers is available. 

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