Uses of Complexing Agents

Most applications of complexing agents depend upon the fact that they will tie up most of the metal ion present in a solution as a complex, leaving only a low concentration of free metal ion. 

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After Baishya et al. isobutyl methyl ketone extracts "Tc from the decay products of " Mo-labelled molybdate in the pH range 0.5-13.0. The use of complexing agents is unnecessary. 

Among the solution-growth methods, crystallization from aqeous solution is well known. Materials with low water solubility may be brought into solution by the use of complexing agents (mineralizers). Selenium, for instance, can be grown from aqueous sulphide solutions, by making use of the reaction... 

The use of complexing agents in organic solvents is not widespread because metal ions more often are determined in aqueous solution this is an area where further research may prove fruitful. 

Other variations of the principle to render the analyte non-extractable in the acceptor involve the use of complexing agents. These form charged complexes in the acceptor, preventing back-extraction. The use of DTPA for trapping of metal ions, as described above in Section 12.3.3, is a good example on this. 

The use of complexing agents for the elution of chemically similar ions is extremely important in the separation of the rare earths and... 

Separation Restricted to physical, predominantly non-selective interactions between the separated substances and the stationary phase Efficient enough as a result of additional use of (1) sufficiently strong interactions between the analyte and the stationary phase (e.g., use of complexing agents) and (2) chemical reactions whose products are separated more easily than the initial substances... 

The metal reactivity, amount of water, solvent, temperature, and the use of complexing agents or catalysts are the main reaction parameters. Whether to use a catalyst or not depends on the chemical nature of the metal atom and steric hindrance of the aUcoxide group. The electrophilic character of the metal atom and its ability to increase the coordination number appears to be the main parameter. This route requires a lower temperature and less energy than physical mixing [135]. 

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