Volumetric behaviour of amino acids and their group contributions in aqueous lactose solutions at different temperatures

Densities, ρ, for glycine, l-alanine, l-valine, and l-leucine [(0.05 to 0.30) m] in aqueous lactose solutions ranging from pure water to 6 mass% lactose were determined at T = (293.15, 298.15, 303.15, and 308.15) K. The density was used to compute apparent molar volume, Vφ  , partial molar volume at infinite dilution, Vϕo, and experimental slope, SV   were obtained and interpreted in terms of solute–solvent and solute–solute interactions. These data were used to calculate the (∂Vϕ0/∂T)P values. The partial molar volume of transfer, ΔVϕ0 from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of Vϕ0 with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH3+COO-, and CH2 groups to Vϕ0.