HIGH-PRESSURE PHASE-EQUILIBRIUM STUDIES FOR THE CARBON-DIOXIDE ALPHA-TOCOPHEROL (VITAMIN-E) SYSTEM

Composition and density measurements at equilibrium in the two-phase region of the system carbon dioxide/dl-alpha-tocopherol (syn. vitamin E) have been conducted from 303 to 353 K and between 100 and 350 bar. A variable volume analytical recirculation apparatus with a directly coupled supercritical fluid chromatograph (SFC) and an oscillating tube densitometer were used for composition and density determination. The results are compared with solubility measurements in the carbon dioxide phase by other authors using in situ near-infrared (NIR) spectrometric and gravimetric sampling methods. A physical property model available in a commercial software package was tested for its capacity to predict and/or regress the measurements.