Solubilities of cholesterol and desmosterol in binary solvent mixtures of n-hexane plus ethanol

The solubilities of cholesterol and desmosterol in binary solvent mixtures of n-hexane + ethanol at temperatures of 293.2-323.2 K were determined by a static equilibrium method. The solubilities increase with temperature and go through a maximum at a specific solvent composition. The fusion enthalpy Delta H-fus and the melting point T-m determined by differential scanning calorimeter (DSC), are 28.5 kJ/mol, 421.7 K for cholesterol and 15.9 kJ/mol, 388.2 K for desmosterol, respectively. The solubilities of cholesterol and desmosterol in pure n-hexane or ethanol follow a linear Van't Hoff relation with temperature. Activity models, such as Wilson, NRTL and UNIQUAC models were used to correlate and predict the solubilities of cholesterol and desmosterol in n-hexane + ethanol mixed solvents. The interaction parameters were expressed as a function of temperature. (C) 2009 Elsevier B.V. All rights reserved.