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

The solubility of metastable alpha-form and stable beta-form of L-glutamic acid in different aqueous solvent mixtures was measured by analytical gravimetric method. The solubility of beta-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 alpha and beta-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. (C) 2010 Elsevier B.V. All rights reserved.