HYDROPHOBIC INTERACTION IN SUGAR SOLUTIONS - RESULTS FROM GEL INTERACTION STUDY

The interaction between ester molecules and Sephadex LH gel in sucrose, glucose and fructose solutions was studied. Sucrose and fructose, like glucose, are not retained in the gel. The void volume, Vo, of the gel is not effected in sugar solutions. Swelling of the gel is reduced in sugar solutions compared to its swelling H2O. Of the 3 sugars, sucrose reduced the swelling most, the effects of glucose and fructose being about equal. Thr retention of the esters in sugar solutions increases where the elution volume of N-acetyl-L-tyrosine ethyl ester (ATYE) in 1.5 M sucrose is 50 ml greater than its elution volume in H2O. To compare retention at different sugar concentrations, an affinity number A = (Ve-Vt)/g is used where Ve is the elution volume of the solute, Vt is the bed volume of the gel, and g is the dry weight of the gel in grams. The affinity of the esters for the gel increases with sugar concentration, the increase being more rapid at higher concentrations of sugar, and increases in sucrose solution as compared with those containing glucose and fructose, the affinity in these latter 2 solutions being nearly equal. The retention of the esters in the gel takes place by hydrophobic interaction. The increased retention in sugar solutions may indicate stronger hydrophobic interaction between ester molecules and gel, indicating that hydrophobicity increases in sugar solutions, with gel hydroxypropyl groups probably being sites of molecular interaction. Possibly ester solubilities in the mobile and stationary phases differ in the absent and presence of sugars. Addition of sugars to H2O probably increases hydrophobic forces between additional groups and molecules present in the system.