Thin layer chromatographic studies of the adsorption behaviour of amino acids through a static soil phase

Abstract

Thin layer chromatography (TLC) has been used as an analytical technique for the identification and monitoring of the adsorption behaviour of 27 amino acids through a static soil flat bed in contact with aqueous solutions of an inorganic electrolyte (ammonium sulphate) and an organic non-electrolyte (urea) at different concentration levels. Certain amino acids showed salting-out and/or salting-in effects over a limited ammonium sulphate concentration range. Using differential adsorption, it was possible to separate closely related amino acids from their mixtures on the soil bed using 0.1 M solutions of ammonium sulphate and urea. In addition to the simultaneous separation of glycine from arginine and glutamic acid, mutual separations of amino acids having non-polar side-chains from amino acids having charged or ionic polar side-chains (basic and acidic) are worthy of mention. The effects of particle size, activation temperature, irradiation of the soil by γ-rays and the pH of the soil bed on the mobility sequence of the amino acids were also examined. The most fascinating aspect of the present study was the adsorption behaviour of amino acids in the presence of cationic, anionic and non-ionic surfactants at different concentration levels.