Solubility of α-form and β-form of l-glutamic acid in different aqueous solvent mixtures

The solubility of metastable α-form and stable β-form of l-glutamic acid in different aqueous solvent mixtures was measured by analytical gravimetric method. The solubility of β-form in ethanol + water, 1-propanol + water and acetone + water at 308 K was investigated and the data were correlated by (CNIBS)/Redlich–Kister equation. The solubility of α and β-form of l-glutamic acid in pure water and ethanol + water mixtures at temperature between 293 K and 328 K were also investigated. Based on the solubility data measured, the dissolution enthalpy and entropy of two forms of l-glutamic acid were determined using van’t Hoff plots.