Selectivity of hydrophilic gel for inorganic ions

Transition metal ions are known to bind to various hydrophilic gel materials in varying degrees, depending upon pH and buffer concentration [ref. 81-83]. 

As for dextran and polyacrylamide gels, the amount of metal bound tends to increase with increasing degree of crosslinking in the gel. Morgan et al. [ref. 

81] assumed that the binding of zinc ion to dextran gels is caused by bonding of the ion on glycopyranosides. 

Limoni and Schmuckler [ref. 37, 38] demonstrated that the anionic complexes of transition metal ions interact strongly with polyacrylamide gels. Based on the kinetic data obtained from breakthrough curves of chioro-complexes of copper, palladium and platinum on Bio-Gel P-2, the rate-determining step in the chromatographic process was found to be the detachment of solute molecules from the functional groups of the gel. 

As well as in organic polymer chemistry, exclusion chromatography has a great potentiality in characterizing inorganic polymers. This technique has been successfully applied not only to separations but also to size estimations of these compounds. Most of the early works have been extensively reviewed by Yoza [ref. 1]. We will thus describe mainly the recent studies on the exclusion chromatography of inorganic polymers reported in the past decade. 

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