Experimental Measurement and Correlation of two α-Amino Acids Solubility in Aqueous Salts Solutions from 298.15 to 323.15 K


By the gravimetric method at atmospheric pressure, the solubility of two ${\alpha}$-amino acids was resolved over temperatures from (293.15 to 323.15) K. The ${\alpha}$-amino acids studied were L-arginine and L-histidine. Results showed a salting-out effect on the solubility of the tested amino compounds. It is obvious that there was an increase in the solubility, in aqueous chloride solutions, with the increasing temperature. Results were translated regarding the salt hydration shells and the ability of the solute to form hydrogen-bond with water. The solubility data was precisely associated with a semiempirical equation. The standard molar Gibbs free energies of transfer of selected α-amino compounds (${\Delta}_{tr}G^{o}$) from pure water to aqueous solutions of the chloride salts have been calculated from the solubility data. The decrease in solubility is correlated to the positive (${\Delta}_{tr}G^{o}$) value which is most part of the enthalpic origin.