Correlation of solid solubilities of pharmaceutical compounds in supercritical carbon dioxide with solution model approach

In this study, the solid solubility data of 15 pharmaceutical compounds in supercritical carbon dioxide at different temperatures and pressures are tried to be correlated with the regular solution model coupled with the Flory-Huggins equation. While correlating the data, the molar volume of the solid solute is considered as a variable consisting of two parameters for the model. This volume is then transformed into a reduced form by introducing the critical density of carbon dioxide and even simplified to be with only one parameter involved. Comparing the correlation results obtained from the commonly used semi-empirical models to the results from the present approach, it is observed that the regular solution model coupled with the Flory-Huggins equation approach is feasible and the results are satisfactory for these complex pharmaceutical compounds in this study. In addition, a further consideration that the only parameter included in the present model could be expressed in terms of the ratio of the molecular weight of compound to that of CO2, and makes the model become a more general and could he applied for prediction. (C) 2012 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.