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

Abstract

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, V φ , partial molar volume at infinite dilution, V ϕ o , and experimental slope, S V were obtained and interpreted in terms of solute–solvent and solute–solute interactions. These data were used to calculate the ( ∂ V ϕ 0 / ∂ T ) P values. The partial molar volume of transfer, Δ V ϕ 0 from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of V ϕ 0 with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH 3 + COO - , and CH 2 groups to V ϕ 0 .