Solubility determination of cholesterol polymorphs in organic solvents.

In a study of the solubility of crystalline forms of cholesterol in various solvents, the solubilities (per cent by weight) of cholesterol needles and hydrated plates at 38#{176} were, respectively, 4.0 and 3.2% in olive oil; 2.6 and 1.9% in tetradecane; 26.2 and 9% in toluene; and 21.0 and 7% in cyclohexane. When these solvents are in equilibrium with an aqueous phase, needles are converted to plates. Pseudomorph (dehydrated) plates in olive oil have the solubility of needles. These differences may have significance in studies involving cholesterol pathogenesis. The modified Zak reaction with ethanol could not be used for the assay of cholesterol in olive oil since the reaction product was turbid. Higher alcohols were studied as a substitute for ethanol; 2-propanol was satisfactory.