The Intracavitary Basis of Solute Partitioning in Dextran (SephadexR) Gels and the Role of Vicinal Water
The partitioning of hydrocarbons and some of their hydroxyl derivatives is described. Two types of solute can be distinguished, non-polar or weakly polar, and polar. The former have an affinity for the gel which appears to involve a hydrophobic interaction and the affinity increases with increasing number of methylene carbons. Polar solutes on the other hand exhibit a reversed type of behaviour, i.e. steric exclusion. The partitioning of all solutes in all the gels can, however, be generalized into a single equation yielding for each gel a generalized logarithmic distribution coefficient. This suggests that although there are different partitioning mechanisms for different solutes, a common structural property of the gel may underlie all partitioning. The structural property best correlated with the generalized distribution coefficient is the concentration of ether oxygens a property which reflects how the matrix changes with increased cross-linking. On a basis of a comparison with the Schardinger cycloamyloses which have similar partitioning properties it is suggested that a cavitary structure is also required and that further, matrix perturbed (vicinal) water may be responsible for the hydrophobic interaction.
KeywordsPolar Solute Polyhydric Alcohol Matrix Concentration Steric Exclusion Hydroxyl Derivative
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