Evaluation and correlation of solubility and solvation thermodynamics of glycine, dl-alanine and dl-valine in aqueous sodium sulphate solutions at two different temperatures.

In the present study the saturated solubilities of glycine, dl -alanine, and dl -valine in aqueous mixtures of Na 2 SO 4 were determined at 298.15 K and 323.15 K by using an analytical ‘gravimetric method’. The nature and extent of such solubilities of the experimental amino acids in aqueous Na 2 SO 4 solutions are discussed in the light of salting-in and salting-out effect and compared with the values of the same amino acids reported earlier. The physicochemical and chemical factors affecting the solubility results were suggested and correlated with the thermodynamical aspects and parameters. Finally the transfer Gibbs free energies were calculated and employed to discuss the relative stability of the amino acids in aqueous and aqueous electrolyte solution. [ABSTRACT FROM AUTHOR]