Phase equilibria in systems containing α-tocopherol and dense gas

Solubility of α-tocopherol in CO2 and propane was determined at temperatures 303, 313, 333 and 353 K and over a pressure range from 79 to 286 bar for CO2 and 16 to 112 bar for propane. A static-analytic method was applied. The solubility of α-tocopherol in dense CO2 under the conditions investigated was in the range of 0.2–17.0 mg/g CO2. The maximal solubilities of α-tocopherol in propane were approximately up to ten times higher than in CO2 and were in the range from 38.9 to 171.9 mg/g propane. Phase equilibrium data for Milk Thistle seed oil in supercritical CO2 were determined at temperatures 313, 333 and 353 K and pressures ranging from 100 to 300 bar. The oil was previously additionally vitaminized and contained 1.9 wt.% of α-tocopherol and 1.7 wt.% of free fatty acids (FFA). The solubility of oil in CO2 was in the range from 1.3 to 17.9 mg/g CO2. The distribution coefficients of α-tocopherol and FFA between light and heavy phase were determined on a solvent free basis. The obtained separation factors increased with temperature and pressure to approximately 160–200 bar and decreased with a further increase of pressure.