Prediction of solubility of biomolecules in supercritical solvents

The supercritical fluid extraction (SFE) is considered an appropriate alternative for separation of biomolecules from food and phamaceutical products. A major difficulty in utilizing the SFE for biomolecules has been the difficulty in measurement and prediction of their solubilities in supercritical solvents at various pressures and temperatures for process optimization. Lack of data for intermolecular energy parameters and/or critical properties, acentric factors, and molar refractions limits us to the use of the simple equations of state for prediction of their solubilities in supercritical solvents. In this report, six different cubic equations of state are used to predict the solubility of cholesterol and beta -carotene, as two representative biomolecules, in supercritical fluids. They are the van der Waals, Redlich-Kwong, Mohsen-Nia-Moddaress-Mansoori (MMM), Peng-Robinson (PR) and Patel-Teja and modified PR equations. It is shown that the two-parameter MMM equation is more accurate than five of the other equations and comparable to the modified PR equation in predicting the solubility of cholesterol and beta -carotene in supercritical fluids. (C) 2001 Elsevier Science Ltd. All rights reserved.