Representation of solid-liquid equilibrium of L-ornithine-L-aspartate + water + methanol system using the Chen model for mixed-solvent electrolyte solution

Solubility measurements were performed in the temperature range of 298-333 K, for a methanol content varying between 0 mass % and 90 mass %. The phase equilibrium condition of L-ornithine-L-aspartate (LOLA) + water + methanol and the mean ionic activity coefficients of LOLA in a ternary system were calculated by using the Chen model, allowing the description of the mixed-solvent electrolyte systems. The mean ionic activity coefficients were calculated with nine binary parameters: six parameters for the binaries LOLA + water (taken from conductance measurements) and water + methanol (taken from the literature) and three parameters for the binary LOLA + methanol (obtained by regression of solubility data). Using binary adjustable parameters and solubility data, the model satisfactorily correlates the ternary (LOLA + water + methanol) system over the entire range of temperature and concentrations.