Solubility determination and thermodynamic data of apigenin in binary {Transcutol®â€¯+ water} mixtures

Solubility and thermodynamic data of apigenin (APG) in binary {2-(2-ethoxyethoxy)ethanol (Transcutol®) + water} mixtures were obtained in this work. The mole fraction solubilities (xe) of APG in binary {Transcutol®â€¯+ water} mixtures were measured at temperature T = 298.15 K to318.15 K and atmospheric pressure p = 0.1 MPa. Solubility values of APG determined in this study were fitted well with four different computational models namely “van't Hoff, Apelblat, Yalkowsky and Jouyban-Acree” models with root mean square deviations of <4.0%. The maximum xe value of APG was recorded in neat Transcutol® (0.382 at T = 318.15 K). However, the minimum xe value of APG was recorded in neat water (1.01 × 10−6 at T = 298.15 K). The values of activity coefficients were also determined for the evaluation of solute-solvent molecular interactions and results suggested higher solute-solvent molecular interaction in APG-Transcutol in comparison with other combinations studied. Apparent thermodynamic analysis suggested endothermic and entropy-driven dissolution of APG in all binary {Transcutol®â€¯+ water} mixtures studied. Enthalpy-entropy compensation analysis suggested enthalpy-driven mechanism as the main mechanism for solvation behavior of APG.