摘要 |
A process of diminishing the concentration of a transition metal complex from a first solution by adding a solubility-enhancing compound that enhances the solubility of said complex in a second solution and extracting the first solution with the second solution. The solubility-enhancing compound is a compound of formula A wherein, R<SUP>a </SUP>is SH, SO<SUB>3</SUB>H, OH or COOH; R<SUP>b </SUP>is SH, OH or COOH; R<SUP>c </SUP>each independently is H, SH, OH or COOH; R<SUP>d </SUP>each independently is H or COOH; n is 1, 2, 3, 4 or 5; or a salt or an activated form thereof.
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