Binary Diffusion Coefficients for Aqueous Solutions of l-Aspartic Acid and Its Respective Monosodium Salt

Although aspartic acid is a non-essential amino acid, its importance is crucial for a major metabolic pathway and it is present in different types of foods. This highlights the need of a better knowledge of its transport properties. A Taylor dispersion technique has been used for measuring mutual diffusion coefficients of binary aqueous solutions of l-aspartic acid, an associated electrolyte, and the corresponding salt sodium l-aspartate, which behaves as a non-associated electrolyte, at 298.15 K and concentrations ranging from (0.001 to 0.100) mol·dm−3. Thermodynamic factors for the diffusion of aspartic acid and sodium aspartate have been estimated on the basis of the Onsager–Fuoss equation. Furthermore, experimental diffusion coefficients of aspartic acid are compared with those computed by the modified Onsager–Fuoss equation, applied for partially dissociated electrolytes.