1958 年 78 巻 4 号 p. 381-386
Vitamins A and D were solubilized in water by the use of various amounts of several non-ionic surface active agents, each solution was heated to 100°, and change in optical density of the solution at different temperatures during cooling was measured by the Coleman spectrophotometer to examine the state of clouding formation. Results obtained were as follows:
1) Turbidity of the solution differed in aqueous solution of the surfactant alone and that in which vitamin A or D had been solubilized, even if the surfactant and its concentration were the same. Turbidity was found to depend on the substance solubilized.
2) The polarity of the solubilized substance seemed to affect turbidity since it was the worst in vitamin A alcohol and vitamin D, followed by A acetate, and practically no change was observed with vitamin A palmitate. This agrees with the fact that there are few changes in non-polar cetane and severe change is seen in polar octyl alcohol.
3) As for the properties of the surfactant, the polymerization degree of ethylene oxide affects turbidity when lipophilic group is the same, the greater the polymerization degree, the less the turbidity.
4) Some of the surfactant was found to give double cloud point, irrespective of the substance being solubilized.
5) When clouding becomes too severe, there occurs separation into two layers or precipitation, which returns to the original state on cooling and mixing.