(456b) Solute Solubility Parameter Determination Using Supercritical Fluids

Solubility parameters can be determined or estimated by several methods, namely: calculation from P-V-T-ρ data and equation of state, measuring a solute’s solubility in a number of liquids of varying solubility parameter, estimated using group contribution methods, Hansen 3-D solubility spheres, and inverse chromatography.  By using appropriate equations for calculating solubility parameters of a sub- or supercritical fluid combined with corresponding states theory, and solute solubility data in supercritical carbon dioxide, ethane, fluoroform, chlorotrifluoromethane, 1,1 – difluoroethane, sulfur hexafluoride, and nitrous oxide – the solubility parameters for a diverse array of solutes have been determined using these dense fluids at pressures up to 2000 bar and temperatures from 40 – 120 C.  This approach which uses the varying solubility parameter as a function of pressure/temperature for one fluid will be compared with solubility parameter data determined using a variety of liquid solvents.  Solubility data from several literature resources (1-3) and unpublished data on complex lipid mixtures will be presented and include solutes such as synthetic antioxidants, beta-carotene, adamantine, dyestuffs, vegetable oils, low molecular weight polystyrenes and polyethylene glycols, polynuclear aromatic hydrocarbons, and synthetic esters.  Comparison of the “supercritical” solvent-derived solubility parameters with those from the literature and calculated by group contribution methods is favorable suggesting this approach can be used to determine solubility parameters for optimizing supercritical fluid extraction and fractionation.  Finally, the application of solubility parameter will be shown to be applicable to rationalizing extraction conditions used in ultrahigh pressure SFE.                 

(1) R.B. Gupta and J-J Shin, “Solubility in Supercritical Carbon Dioxide”, CRC Press, Boca Raton, FL (2007)

(2) T. Kraska, K. O. Leonhard, D. Tuma and G. M. Schneider, Journal of Supercritical Fluids 23 (2002) 209–224

(3) Lyle Bowman, “Dense Gas Chromatographic Studies”, Ph.D. Thesis, University of Utah, 1976