Cluster formation and diffusion in supersaturated binary and ternary amino acid solutions

Abstract

Indirect evidence for the existence of molecular clusters in supersaturated solutions of the binary systems glycine-water and valine-water and the ternary system glycine-valine-water is provided through measurement of diffusion coefficients and through concentration gradient formation in long columns. The binary system diffusion coefficient results show that the diffusion coefficient declines with both time and concentration in the metastable region and that this decline can be accounted for employing a theory of precritical molecular cluster evolution. The ternary system result shows that the concentration of valine seems to increase the tendency of glycine to form molecular clusters. In addition the ternary diffusion coefficient results show that the “cross term” diffusion coefficient (hence the multicomponent diffusive effect) becomes as large as the “main” term coefficient in supersaturated glycine-valine-water solutions.