Trace element analysis biological materials

Both flame and graphite furnace atomic absorption spectrometry are two of the commonest techniques used for the determination of metals and metalloids. Various authors " have discussed the application of both to the analysis of trace elements in biological materials. 

Other Metal-Peptide and -Protein Interactions.—The determination of protein-bound trace elements in biological material by neutron activation analysis has been described Zn, Hg, Cu, and Se were accurately detected in human liver samples, provided that most of the element concerned was protein bound. An interaction of mercury with a protein or a protein-DNA complex has been invoked to explain the partitioning of the metal in euchromatin over heterochromatin (from mouse liver nuclei) by a 10 1 ratio. " Bovine retinas, isolated rod outer segments and emul-phogene extracts of rod outer segments have been shown to contain appreciable amounts of Zn ", Ca and the zinc levels being light sensitive. 

Norheim C, Steinnes E. 1975. Determination of protein-bound trace elements in biological materials by gel filtration and neutron activation analysis. Anal Chem 47 1688. 

Sansoni B and Iyengar V (1978) Sampling and Sample Preparation Methods for the Analysis of Trace Elements in Biological Material. Spezielle Berichte Kemforschungsanlage Jiilich, JUL-Spez-13. 

Wurfels, M. and Jackwerth (1985). Investigations of the carbon balances in decomposition of biological materials with nitric acid, Fres. Z. Anal. Chem. 322,35-58 Yin, D. and Wang, Y. (1987). Analytical problems of trace elements In biological materials. Part 2. Sources of analytical errors in trace element analysis of biological materials, Zhong. Huan. Hexue 7(2), 67-71... 

Cornells, R., Hoste, J. and Versieck. J. p982). Potential interferences inherent in neutron-activation analysis of trace elements in biological materials. Talanta 29,1029. 

Norheim, G. and Steinnes, E. 975). Determination of Protein-Bound Trace Elements in Biological Material by Gel Filtration and Neutron Activation Analysis. Anal. Chem., 47, 1688. 

Some of the difficulties in the unbiased determination of certain trace elements in biological materials may be due to problems of speciation. The range of complex organo-metallic species that can be found in nature is very wide (Frausto da Silva and Williams, 1991). In carrying out an analysis for a particular element in any type of biological fluid or tissues, major assumptions are made concerning the precise chemical composition of element species present. Different analytical techniques will have different sensitivities towards particular element species. Much of the early understanding of the special analytical problems posed by element speciation comes from studies of arsenic (Buchet et al., 1980 Buchet et al., 1981) and mercury (Clarkson, 1983). Problems with other metals remain to be resolved and may require considerable analytical sophistication such as in the analysis of chromium speciation (Urasa and Nam, 1989). 

Versieck j, Hoste j, Vanballenberghe L, De Kesel A, Van Renterghem DJ (1987) Collection and preparation of a second generation biological reference material for trace element analysis. J Radioanal Nucl Chem 113 299-304. 

Byrne AR, Deemelj M, Kosta L, and Tusek-Znidaric M (1984) Radiochemical neutron activation analysis in standardization of trace elements in biological reference materials at the nanogram level. Mikrochim Acta [Wien] 1 119-126. 

Parr RM (1980) The reliability of trace element analysis as revealed by analytical reference materials. In Bratter P, Schramel P, eds. Trace Element Analytical Chemistry in Medicine and Biology, pp 631-655. Walter de Gruyter Co., New York. 

Two methods were examined for digestion of biological samples prior to trace element analysis. In the first one a nitric acid-hydrogen peroxide-hydrofluoric acid mixture was used in an open system, and in the second one nitric acid in a closed Teflon bomb. The latter method was superior for Ge determination, however, germanium was lost whenever hydrogen fluoride had to be added for disolving sihcious material. End analysis by ICP-AES was used for Ge concentrations in the Xg/g range13. 

Various reference materials have been described, to help improving the reliability of trace elemental analysis of lead and other heavy elements, for clinical and environmental applications. Such materials include blood10,11, diets, feces, air filters, dust11, foodstuffs12 and biological tissues13. 

Both microwave closed-vessel dissolution and laboratory robotics are relatively new to the analytical laboratory. However, it is this marriage of new methods which provides useful combinations of flexible laboratory automation to meet a variety of individualized needs. Because of the large number of biological samples which are prepared for analysis each day, it is reasonable to assume that this type of innovative automation wiU be of great benefit. It should be evaluated for its ability to improve the preparation technology for trace element analysis of biological materials. 

Boyer KW, Horowitz W. 1986. Special considerations in trace element analysis of foods and biological materials. In O Neill IK, Schuller P, Fishbein L, eds. Some metals As, Be, Cd, Cr, Ni, Pb, Se, Zn. lARC Scientific Publication No. 71, Lyon, France International Agency for Research on Cancer, 191-220. 

H. Matusiewicz, R.E. Sturgeon, S.S. Berman, Trace element analysis of biological material following pressure digestion with nitric acid-hydrogen peroxide and micro-wave heating, J. Anal. At. Spectrom. 4 (1989) 323-327. 

R. G. L. Silva, S. N. Willie, R. E. Sturgeon, R. E. Santelli, S. M. Sella, Alkaline solubilization of biological materials for trace element analysis by electrothermal atomic absorption spectrometry, Analyst, 124 (1999), 1843D1846. 

The forensic scientist employed in the analysis of specimens for metal concentrations is involved generally in two main areas of investigation. The first is in the determination of toxic metals in biological tissue in order to ascertain the cause of death or injury (homicidal or suicidal) in suspected poisoning cases. The second is to compare certain characteristic trace element concentrations in materials found at the scene of the crime with the same type of material found in the possession of the accused. A special case of this second approach is in the analysis of the elements barium,... 

Sansoni, B., Panday, V.K. Ashing in trace element analysis of biological material. In Fachetti, S. (ed.) Analytical Techniques for Heavy Metals in Biological Fluids, pp. 91-131. Elsevier, Amsterdam (1983)... 

Mader, P., Szakova, J., Curdova, E. Combination of classical dry ashing with stripping voltammetry in trace element analysis of biological materials review of literature published after 1978. Talanta 43, 521-534 (1996)... 

Examples of applications of X-ray spectrometric analytical techniques to elemental determinations in a variety of materials are presented in Table 2.12. Some recent applications papers may be mentioned. Total reflection XRF has been applied by Xie et al. (1998) to the multielement analysis of Chinese tea (Camellia sinensis), and by Pet-tersson and Olsson (1998) to the trace element analysis of milligram amounts of plankton and periphyton. The review by Morita etal. (1998) on the determination of mercury species in environmental and biological samples includes XRF methods. Alvarez et al. (2000) determined heavy metals in rainwaters by APDC precipitation and energy dispersive X-ray fluorescence. Other papers report on the trace element content of colostrum milk in Brazil by XRF (da Costa etal. 2002) and on the micro-heterogeneity study of trace elements in uses, MPI-DING and NIST glass reference materials by means of synchrotron micro-XRF (Kempenaers etal. 2003). 

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