Solubility of capsaicin and ß-carotene in supercritical carbon dioxide and in halocarbons

The solubilities of beta -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 beta -carotene was also measured in 1,1,1-trifluoroethane (R-143a). The temperatures of the measurements ranged from 35 degreesC to 55 degreesC for capsaicin (up to 85 degreesC in R-32) and from 40 degreesC to 70 degreesC for beta -carotene. The solubilities were determined using an HPLC system for capsaicin and a static high-pressure cell for beta -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 beta -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 Mendez-Santiago and Teja.