Correlation of solid solubility for biological compounds in supercritical carbon dioxide: comparative study using solution model and other approaches

Solid solubility of biological compounds in supercritical carbon dioxide was calculated using the solution model approach. These biological solutes include steroids, antioxidants, xanthines, drugs and heavy aromatic compounds. The regular solution model coupled with the Flory-Huggins equation was employed. The molar volume of the solute in the supercritical phase was optimally fitted for each biological compound using the experimental solubility data. With two parameters in the solution model. satisfactory results of solid solubility were obtained which are comparable to those calculated from the equation-of-state method or semi-empirical equations with more adjustable parameters. The parameters in the solution model also show regular correlation with the pure component property of the complex solutes. (C) 2002 Elsevier Science B.V. All rights reserved.