Chelating heavy metal

Another method employed is the treatment of aqueous solutions of aminophenols with activated carbon (81,82). During this procedure, sodium sulfite, sodium dithionite, or disodium ethylenediaminotetraacetate (82) is added to increase the quaUty and stabiUty of the products and to chelate heavy-metal ions that would catalyze oxidation. Addition of sodium dithionite, hydrazine (82), or sodium hydrosulfite (83) also is recommended during precipitation or crystallization of aminophenols. 

Chelates Heavy metals or bases Chelating agents such as by extraction of the metal ions Formation of stable metal chelates ... 

Dexrazoxane (Zinecard) [Chelating Agent] Uses Prevent anthracycline-induced (eg, doxorubicin) cardiomyopathy Action Chelates heavy metals binds intracellular iron prevents anthracycline-induced free radicals Dose 10 1 ratio dexrazoxane doxorubicin 30 min prior to each dose, 5 1 ratio w/ CrCl <40 mL/min Caution [C, ] Contra Component sensitivity Disp Inj SE -1-BM (esp leukopenia), fever, Infxn, stomatitis, alopecia, NA /D Interactions t Length of muscle relaxation Wf succinylcholine EMS Given concurrent w/a chemo agent for treating CA to prevent cardiotox monitor for Infxn and reduced cardiac Fxn use caution w/ succinylcholine, reduced doses may be needed OD May cause extreme BM suppression symptomatic and supportive... 

Ethylenediaminetetracetic acid (EDTA), usually as the di-sodium salt, is added to a concentration of 1 mM to chelate heavy metal ions, which can inhibit enzymes at very low concentrations, and also to remove Ca2+ and Mg2+, which can otherwise act... 

Edetic acid and edetate salts are used in pharmaceutical formulations, cosmetics, and foods as chelating agents. They form stable water-soluble complexes (chelates) with alkaline earth and heavy metal ions. The chelated form has few of the properties of the free ion, and for this reason chelating agents are often described as removing ions from solution this process is also called sequestering. The stability of the metal-edetate complex depends on the metal ion involved and also on the pH. The calcium chelate is relatively weak and will preferentially chelate heavy metals, such as iron, copper, and lead, with the release of calcium ions. For this reason, edetate calcium disodium is used therapeutically in cases of lead poisoning see also Section 18. 

Ten different adsorbents were chosen for the present evaluation. They include four types of adsorbents (1) inorganic activated alumina and bone char adsorbents, (2) macroporous cation exchange resins, (3) macroporous anion exchange resins, and (4) chelating heavy metal removal agents. Equilibrium adsorption of Pu(IV) from actual PFP wastewater spiked with a Pu tracer was measured for each of the adsorbents. The plutonium tracer was required because the activity of plutonium in the wastewater was too low to be measured conveniently. Those adsorbents that adsorbed plutonium strongly were then tested in column flow-through experiments and the rate of plutonium adsorption was measured. 

Figure 6. Pu(IV) Distribution Coefficients for Chelating Heavy Metal Removal Agents as a Function of pH.

Histidine-containing protein Chelated heavy-metal... 

Peptides in higher plants can be divided into two major categories. Some have unique structures and functions, whereas others are involved in the synthesis or degradation of proteins (Higgins and Payne, 1982). In this treatment, emphasis will be given the former type. There are limited data concerning peptides of either type from plants, A series of peptides known as phytochelatins has been shown to chelate heavy metals. A number of plants, including those of certain members of the Celastraceae, Euphorbiaceae, and Rhamnaceae, contain peptide alkaloids which are discussed under Peptide and Macrolide alkaloids (Chapter 37). A num-... 

This ability to chelate heavy metal ions has been brought forward to account for some pharmacological activities shown by flavonoid compounds. Clark and Geissman showed, however, that the potentiation of effects of epinephrine by flavonoid compounds, tested upon an isolated smooth muscle preparation and attributable to the metal-chelating properties of the compounds, did not correspond with their vitamin-P activities as reported in the literature (c/. p. 275). 

DTT and DTE chelate heavy metal ions tightly, which can be helpful at times, but deleterious with autooxidizable ions such as Fe . While they oxidize only slowly in air in the absence of heavy metal ions, DTT and DTE are readily oxidized in air in the presence of Fe , so solutions containing Fe and DTT must be kept anaerobic. ... 

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