Thermodynamic studies of fluphenazine decanoate solubility in PEG 200 + water mixtures

The solubility of fluphenazine decanoate (FD) in binary mixtures of polyethylene glycol 200 (PEG 200) + water at the temperature range from 298.0 K to 318.0 K is reported. The previously trained version of the Jouyban–Acree model for PEG 200 + water, a recently proposed general cosolvency model employing partial solubility parameters, and a combination of the model with van’t Hoff equation were used to predict the solubility of FD in PEG 200 + water at different temperatures. The results show that the Jouyban–Acree model can be used for solubility prediction of FD in PEG 200 + water mixtures at different temperatures. The solubility data as a function of temperature were used to determine the thermodynamic properties of the dissolution process including Gibbs energy, enthalpy and entropy of the solution. An adapted version of the model is used to represent the thermodynamic properties of the solutions in the solvent mixtures and the obtained results were satisfactory. Densities of solute free PEG 200 + water and FD-saturated solutions are also reported.