Partial molar volumes and compressibilities of α-amino acids from aqueous to aqueous-disodium tartrate solutions at T = (303.15, 308.15 and 313.15) K

Abstract

Present work reports the densities (ρ) and ultrasonic velocities (u) of four α-amino acids (viz. glycine, l-proline, l-arginine and l-asparagine) in aqueous disodium tartrate (Na2Tar) (0.50, 1.00 and 1.50 mol·kg−1) solutions at T = (303.15, 308.15 and 313.15) K. Apparent molar volumes (V2, ϕ) and apparent molar isentropic compressibilities (κS, 2, ϕ) of amino acids have been calculated from density and ultrasonic velocity data respectively. Standard molar volumes (V2, ϕo) and standard molar compressibilities (κS, 2, ϕ0) were determined from the graphical fittings using standard relations and corresponding standard transfer volumes (ΔtV2, ϕo) and standard transfer compressions (ΔtκS, 2, ϕ0) were calculated. Different thermodynamic parameters have been used to explore solute-solute, solute-solvent interactions and effect of disodium tartrate salt on the hydration and electrostriction behavior of amino acids. A significant effect of added salt on the volumetric and acoustic behavior of studied amino acids through ion-ion, ion hydrophilic-hydrophilic and hydrogen bonding interactions has been observed.