Calorimetric study of the α-tocopherol solubility in reversed AOT micelles

The experimental data of heat of mixing (Q) for heterogeneous system α-tocopherol/AOT/n-heptane with and without water at 25 °C are presented. The Q dependence on AOT (sodium bis (2-ethylhexyl) sulfosuccinate) concentration, and R parameter defined as R=[H2O]/[AOT] with flow calorimetric method were investigated. Using the D'Aprano model (which is formally identical to that used earlier by Magid et al.) the binding constant (K), the distribution constant of α  -tocopherol (KdistrKdistr) between hydrocarbon and the micellar phase, and the standard enthalpy of transfer (ΔHtr0) of α-tocopherol from the hydrocarbon to AOT reversed micelles were calculated. The solubility of α-tocopherol in AOT reversed micelles explored with the calorimetric technique was compared to the literature data obtained respectively with UV spectrophotometry for reversed micelles and by other techniques for the phospholipid bilayer.

The nonlinear regression (blue line) of the heat of mixing data of α-tocopherol/n-heptane +AOT/n  -heptane solutions (dots) involved to evaluate ΔHtr0 of α-tocopherol from n-heptane to AOT reversed micelles.Figure optionsDownload as PowerPoint slide