Of chelating agent

Table 1 Hsts a number of chelating agents, grouped according to recognized stmctural classes. Because systematic nomenclature of chelating agents is frequently cumbersome, chelants are commonly referred to by common names and abbreviations. For the macrocyclic complexing agents, special systems of abbreviated nomenclature have been devised and are widely used. Some of the donor atoms involved ia chelation and the many forms ia which they can occur have been reviewed (5).

The product is equal to the equilibrium constant X for the reaction shown in equation 30. It is generally considered that a salt is soluble if > 1. Thus sequestration or solubilization of moderate amounts of metal ion usually becomes practical as X. approaches or exceeds one. For smaller values of X the cost of the requited amount of chelating agent may be prohibitive. However, the dilution effect may allow economical sequestration, or solubilization of small amounts of deposits, at X values considerably less than one. In practical appHcations, calculations based on concentration equihbrium constants can be used as a guide for experimental studies that are usually necessary to determine the actual behavior of particular systems. 

DispEcement. In many of the appHcations of chelating agents, the overall effect appears to be a displacement reaction, although the mechanism probably comprises dissociations and recombinations. The basis for many analytical titrations is the displacement of hydrogen ions by a metal, and the displacement of metal by hydrogen ions or other metal ions is a step in metal recovery processes. Some analytical pM indicators function by changing color as one chelant is displaced from its metal by another. 

Katoh, M., Influence of Chelating Agent (Citric Acid) and F on Corrosion of Aluminium , Corros. Sci., 8, 423 (1968)... 

Addition of chelating agents to the fermentation medium may help to inhibit phage multiplication by prevention of phage adsorption to the cell wall. 

The thermal dissociation of chelating agents and chelates of analytical interest. W. W. Wendlandt, Chelates Anal. Chem., 1967,1,107-143 (65). 

Bulman RA (1978) Chemistry of Plutonium and the Transuranics in the Biosphere. 34 39-77 Bulman RA (1987) The Chemistry of Chelating Agents in Medical Sciences. 67 91-141 Burdett JK (1987) Some Structural Problems Examined Using the Method of Moments. 65 29-90... 

Moshonas (1958) investigated the reactions between zinc oxide and a large number of chelating agents. Of these, EBA proved to be the most promising. They then examined cement formation between EBA and various metal oxides. Cement formation was found with MgO, CaO, BaO, ZnO, CdO, HgO and PbO. 

A. Wallace, Effect of chelating agents on uptake of trace metals when chelating agents are supplied to soil in contrast to when they are applied to solution culture. J. Plant Niitr. 2 171 (1980). 

The use of chelating agents may also be a very effective means of immobilizing metals. 

Laughlin NK University of Wisconsin, Madison, Wl Validate the efficacy of chelation agents such as succimer (dimercaptosuccinic acid, DMSA) not only to reduce body lead stores in young children but also to alleviate neurobehavioral and target organ toxicity (Rhesus monkey) National Institute of Environmental Health Sciences... 

Chisolm JJ Jr. 1968. The use of chelating agents in the treatment of acute and chronic lead intoxication in childhood. J Pediatr 73 1-38. 

Hammond PB. 1971. The effects of chelating agents on the tissue distribution and excretion of lead. Toxicol Appl Pharmacol 18 296-310. 

Porru S, Alessio L. 1996. The use of chelating agents in occupational lead poisoning. Occup Med 46(1)41-48. 

---