Solubility of Capsaicin and β-Carotene in Supercritical Carbon Dioxide and in Halocarbons

The solubilities of β-carotene and capsaicin have been measured in supercritical carbon dioxide and in difluoromethane (R-32) and 1,1,1,2-tetrafluoroethane (R-134a) in the liquid phase at temperatures near and somewhat below their critical points. The solubility of β-carotene was also measured in 1,1,1-trifluoroethane (R-143a). The temperatures of the measurements ranged from 35 °C to 55 °C for capsaicin (up to 85 °C in R-32) and from 40 °C to 70 °C for β-carotene. The solubilities were determined using an HPLC system for capsaicin and a static high-pressure cell for β-carotene, and the amounts of products extracted were measured spectroscopically. At similar temperatures and densities, the solubility of capsaicin in the halocarbons was higher than that in carbon dioxide; there was not such a clear trend for β-carotene. Where the data covered a sufficient density range, they (along with literature data for the solutes in carbon dioxide) were analyzed with the semiempirical density-based model of Méndez-Santiago and Teja.