Densities of L-alanine in aqueous LiNO₃, NaNO₃, KNO₃ and NaClO₄ solutions have been measured at 298.15 K with an Anton Paar Model 55 densimeter. Apparent molar volumes, limiting partial molar volumes and transfer partial molar volumes have been calculated. Hydration numbers and volumetric interaction coefficients for L-alanine were evaluated. The transfer partial molar volumes from water to oxacid salt solutions have been discussed in terms of electrostatic interaction and structural interaction. The results show that all the transfer partial molar volumes of L-alanine are positive and increase with the increasing concentration of salts. The reduction in the electrostriction with increasing concentration of salts was confirmed by the decreased hydration number. The contribution of electrostatic interaction to transfer partial molar volumes is predominant. Electrostatic interaction is responsible for the trends of transfer partial molar volumes in NaNO₃, KNO₃ and NaClO₄ solutions, while in LiNO₃ solutions the influence of structural interaction is prominent.

Key words: L-alanine, oxacid salt, limiting partial molar volume, electrostatic interaction, structural interaction