Eur. Phys. J. E (2017) 40: 21
https://doi.org/10.1140/epje/i2017-11511-y

Regular Article

Limiting values of diffusion coefficients of glycine, alanine, -amino butyric acid, norvaline and norleucine in a relevant physiological aqueous medium

¹ Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia Sede Bogotá, Calle 44 No. 45-67, Bloque B-09, Bogotá D.C., Colombia
² Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal
³ U.D. Química Física, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain

^* e-mail: miguel.esteso@uah.es
^** e-mail: anacfrib@ci.uc.pt

Received: 29 September 2016
Accepted: 2 February 2017
Published online: 27 February 2017

Abstract

The side chain effect on transport in ionic aqueous salt solutions was investigated for -amino acids glycine, alanine, -amino butyric acid, norvaline, and norleucine --that together define a chemical homologous series based on the length of the characteristic side chain which increases from zero to four carbons, respectively. Binary mutual diffusion coefficients at infinitesimal concentration in aqueous solutions of NaCl (0.15 mol kg ^-1) are measured by means of Taylor dispersion technique for this series and significant differences were found against previous published results for identical systems in pure water. In this way, NaCl effect on the transport of each amino acid is thus assessed and discussed in terms of salting-out effects. Also, solvated Stokes hydrodynamic radii were computed for the series showing comparable results in water and NaCl solution. The new information should prove useful in the design and characterization of transport-controlled systems in physiological and pharmacological studies.