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 syste m. Quantitation was performed by direct injection of an aliquot of the saturated supercritical solution into a high performance liquid chrom atograph. Solubility was studied at temperatures of 310, 320, 330 and 340 K and pressures from 9 to 28 MPa. The mole fractions of beta-carot ene 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 dissolutio n and for quantitation, The solubility data were correlated by a densi ty-based equation as proposed by Chrastil, and modeled by using the Pe ng-Robinson equation of state. Because of the inaccuracy of the model when the critical parameters of the solute were estimated from group c ontributions, the data were regressed considering the interaction coef ficient k(ij), the critical pressure and the sublimation pressure of p -carotene as adjustable parameters. (C) 1997 Elsevier B.V.