Gas-Liquid Chromatography and Group Contribution Methods for Phase Equilibria in Mixtures Containing Tocopherols

Poster 71n presentato all'AIChE Annual Meeting, Miami (FL - USA), 15-20 novembre 1998. - All natural or synthetic materials undergo reactions with natural oxygen. For the human body to avoid the oxidative damage is one of the most important problem that must be solved in order to keep a good health state. Oxidative processes are involved in premature ageing, reduced immune function, inflammation and degenerative diseases. Once more these oxidation reactions have to be eluded also to preserve food degradation. A proper addition of compounds with antioxidant properties can maintain under control the oxidative reactions both in foods and in human body. Tocopherols, due to their antioxidant properties, are strongly used in pharmaceutical, food and cosmetic fields. The different chemical structures of the compounds classified as tocopherols are responsible of the different behaviour of these compounds in respect to organic solvents. In this work the chromatographic technique is applied for the experimental determination of activity coefficients at infinite dilution of different organic solvents in tocopherols. The experimental information has been correlated with UNIFAC model: the available set of parameters does not allow a satisfactory description of phase equilibria of systems containing tocopherols. A new characteristic group has been defined in order to improve the thermodynamic description of the behaviour of these systems