Contribution to the determination of the solubility of beta-carotene in supercritical carbon dioxide and nitrous oxide: Experimental data and modeling

The solubilities of beta-carotene in supercritical carbon dioxide and nitrous oxide have been measured using a dynamic multi-pass flow system. Quantitation was performed by direct injection of an aliquot of the saturated supercritical solution into a high performance liquid chromatograph. Solubility was studied at temperatures of 310, 320, 330 and 340 K and pressures from 9 to 28 MPa. The mole fractions of beta-carotene were in the ranges 10(-8)-10(-6) mol mol(-1) in carbon dioxide and 10(-7)-10(-5) mol mol(-1) in nitrous oxide. The results were compared with data from the literature. The discrepancies observed within the various studies are discussed regarding the method used for dissolution and for quantitation, The solubility data were correlated by a density-based equation as proposed by Chrastil, and modeled by using the Peng-Robinson equation of state. Because of the inaccuracy of the model when the critical parameters of the solute were estimated from group contributions, the data were regressed considering the interaction coefficient k(ij), the critical pressure and the sublimation pressure of p-carotene as adjustable parameters. (C) 1997 Elsevier B.V.