Heavy metal absorption

Baker EL, Hayes CG, Landrigan PH, et al. 1977. A nationwide survey of heavy metal absorption in children living near primary copper, lead, and zinc smelters. Am J Epidemiol 106(4) 261-273. 

Baser ME, Marion D. 1990. A statewide case registry for surveillance of occupational heavy metals absorption. Am J Pub Health 80(2) 162-164. 

Assadian, N., and Fenn, L. B. (2001). Rhizosphere chemical changes enhance heavy metal absorption by plants growing in calcareous soils. In Trace Elements in the Rhizosphere, ed. Gobran, G. R., Wenzel, W. W., and Lombi, E., CRC Press, Boca Raton, FL 43-60. 

Too many industries currently produce varying concentrations of heavy metal laden waste streams with undesired consequences for the environment. Increasing emphasis has been placed on environmental impact minimization. This has led to the search for natural, inexpensive materials able to remove metals from factory effluents. Heavy metal absorption capacities of modified cellulose materials are found to be significant and their levels of uptake are comparable, in many instances, to other naturally occurring absorbent materials and to commercial ion exchange type resins. Many of the modified cellulose adsorbents proved to be regenerable and reusable over a number of absorption/desorption cycles. This allows easy recovery of the absorbed heavy metals in a concentrated form [22]. 

Fenn, L.B., Assadian., N., 1999. Can rhizosphere chemical changes enhance heavy metal absorption hy plants growing in calcareous soil In Wenzel, W.W., Adriano, D.C., Alloway, B., Doner, H.E., Keller, C., Lepp, N.W., Mench, M., Naidu, R., Pierzynski, G.M. (Eds.), Proceedings of Extended Abstracts, Fifth International Conference on the Biogeochemistry of Trace Elements, Vienna, pp. 154—155. 

Kostial K, Rabar I, Blanusa M, Landeka M (1979) Influence of age on heavy metal absorption. Proc. Nutr. Soc 38 251-256... 

Analysis of Trace or Minor Components. Minor or trace components may have a significant impact on quaHty of fats and oils (94). Metals, for example, can cataly2e the oxidative degradation of unsaturated oils which results in off-flavors, odors, and polymeri2ation. A large number of techniques such as wet chemical analysis, atomic absorption, atomic emission, and polarography are available for analysis of metals. Heavy metals, iron, copper, nickel, and chromium are elements that have received the most attention. Phosphoms may also be detectable and is a measure of phosphoHpids and phosphoms-containing acids or salts. 

Chemical Properties. Elemental analysis, impurity content, and stoichiometry are determined by chemical or iastmmental analysis. The use of iastmmental analytical methods (qv) is increasing because these ate usually faster, can be automated, and can be used to determine very small concentrations of elements (see Trace AND RESIDUE ANALYSIS). Atomic absorption spectroscopy and x-ray fluorescence methods are the most useful iastmmental techniques ia determining chemical compositions of inorganic pigments. Chemical analysis of principal components is carried out to determine pigment stoichiometry. Analysis of trace elements is important. The presence of undesirable elements, such as heavy metals, even in small amounts, can make the pigment unusable for environmental reasons. 

Various methods can be used to analy2e succinic acid and succinic anhydride, depending on the characteristics of the material. Methods generally used to control specifications of pure products include acidimetric titration for total acidity or purity comparison with Pt—Co standard calibrated solutions for color oxidation with potassium permanganate for unsaturated compounds subtracting from the total acidity the anhydride content measured by titration with morpholine for content of free acid in the anhydride atomic absorption or plasma spectroscopy for metals titration with AgNO or BaCl2 for chlorides and sulfates, respectively and comparison of the color of the sulfide solution of the metals with that of a solution with a known Pb content for heavy metals. 

DETERMINATION OF HEAVY METALS IN ATMOSPHERIC PARTICLES (PM 10 PM 2.5) BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY... 

In this work, atmospheric particles (PM 10 and PM 2.5) were collected by a dichotomos air sampler. Several leaching procedures were investigated for decomposition of heavy metals. The digests were pre-concentrated with sodium diethyldithiocarbamate. The determinations were canted out on a Vartan Model AA-220 atomic absorption spectrometer. The instrarment was equipped with a GTA-110 graphite furnace system. Table 1 shows the concentrations of heavy metals associated with PM 10 and PM 2.5 particles. Table 1. Concentrations of heavy metals in PM 10 and PM 2.5 atmospheric particles (ng/m )... 

The effect of a way of obtaining ChCS, time of realization of a sorption, temperature of a sorption, density and pH of sorbate on process of a sorption was studied. It is established, that chitincontaining sorbents ai e strong at pH<5 and are capable for effective heavy metals ions absorption from acid water solutions. 

Heavy metal contamination of pH buffers can be removed by passage of the solutions through a Chelex X-100 column. For example when a solution of 0.02M HEPES [4-(2-HydroxyEthyl)Piperazine-l-Ethanesulfonic acid] containing 0.2M KCl (IL, pH 7.5) alone or with calmodulin, is passed through a column of Chelex X-100 (60g) in the K" " form, the level of Ca ions falls to less than 2 x 10" M as shown by atomic absorption spectroscopy. Such solutions should be stored in polyethylene containers that have been washed with boiling deionised water (5min) and rinsed several times with deionised water. TES [, N,N, -Tetraethylsulfamide] and TRIS [Tris-(hydroxymethyl)aminomethane] have been similarly decontaminated from metal ions. 

Again, it is to be leinembercd tliai only a fraction of the heavy metals gels into the tea. Owing to the very low concentrations, analyses are only possible by means of atomic absorption spectroscopy, after di gesting the drugs with perchloric acid/nilrie acid (hence not in the pharmacy laboratory). 

Discussion. Because of the specific nature of atomic absorption spectroscopy (AAS) as a measuring technique, non-selective reagents such as ammonium pyrollidine dithiocarbamate (APDC) may be used for the liquid-liquid extraction of metal ions. Complexes formed with APDC are soluble in a number of ketones such as methyl isobutyl ketone which is a recommended solvent for use in atomic absorption and allows a concentration factor of ten times. The experiment described illustrates the use of APDC as a general extracting reagent for heavy metal ions. 

The samples have two important characteristics that facilitate these very difficult determinations First, the matrix (all of the sample but the element being determined) is essentially organic matter containing only traces of heavy metals. Second, the samples are of less than critical thickness (6.4). As a consequence, absorption and enhancement effects (7.3) are absent and the scattered background is relatively weak (7.4). 

Sediment pollution. The concentrations of pollutants in the dated sediment cores have been determined in our laboratory by atomic absorption spectrophotometry (AAS). Donazzolo et al. (15) and Pavoni et al. (16) reported mainly heavy metal concentrations. Marcomini et al. (17) and Pavoni et al. (18) discussed the concentration profiles of organic pollutants such as chlorinated hydrocarbons and polycyclic aromatic hydrocarbons. 

Applications EXAFS spectroscopy is obviously well suited to speciate and quantify the state of heavy metals, e.g. in soils [310]. Similarly, it allows differentiation of ZnO and Zn stearate on the basis of the X-ray absorption structure of zinc. 

First step of the approach is the chemical characterization of leachate using well-established analytical techniques (Fig. 2) GC-MS for polar organic compounds (POCs), HRGC-MS for PCDD/Fs, PCBs and PAHs [18], atomic absorption spectrometry for heavy metals and ion chromatography for ammonia. 

Recycling of printer circuit boards is deemed as the most important source of heavy metals to the ambient environment. These heavy metals may be entering into human body from various exposure routes such as ingestion, inhalation, and dermal absorption. Exposure to high levels of heavy metals can lead to acute and chronic toxicity, such as damage to central and peripheral nervous systems, blood composition, lungs, kidneys, liver, and even death [14],... 

Why are barium- and iodine-based materials selected for contrast media The production of X-ray images depends on the differences between the X-ray absorbing power of various tissues. This difference in absorbing power is called contrast and is directly dependent on tissue density. To artificially enhance the ability of a soft tissue to absorb X-rays, the density of that tissue must be increased. The absorption by targeted soft tissue of aqueous solutions of barium sulfate and iodized organic compounds provides this added density through the heavy metal barium and the heavy nonmetal iodine. 

Phytate (myo-inositol hexaphosphate Fig. 15.3, structure 33) is found in many food species and can be considered as a phytochemical. Its role in the plant is primarily as a phosphate store in seeds, but it is found in other tissues as well, for example, tubers (Harland et al., 2004). Phytate and its hydrolysis products are anti-nutrients that chelate metal ions and thus reduce their bioavailability (Persson et al., 1998 House, 1999). This is particularly a problem with cereal grains, but pre-processing can improve mineral absorption from these foods (Agte and Joshi, 1997). There is some concern that high phytate foods could also contain higher levels of toxic heavy metals caused by natural accumulation. Plants also contain phytate-degrading enzymes that can also influence metal ion bioavailability (Viveros et al., 2000). 

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