Use of a water-in-oil microemulsion as mobile phase in complexation TLC of amino acids on silica layers impregnated with metal cations

A water-in-oil microemulsion has been used for the first time as a mobile phase in thin-layer chromatography of amino acids. A new TLC system comprising silica gel layers impregnated with micellar copper sulfate solution as stationary phase and a water-in-oil microemulsion as mobile phase has been proposed for selective Separation Of DL-phenylalanine from other amino acids. Experimental conditions have been optimized and TLC conditions for separation Of DL-phenylalanine in the presence of foreign impurities were determined. Improved separation of amino acids, but with reduced sensitivity, was realized on silica gel layers impregnated with metal ions such as Li+, Cu2+, Ni2+ Zn2+ Cd2+, Hg-2, and Th4+. Silica gel impregnated with a 1:1 mixture of 2% aqueous CuSO4 and 3% Brij-35 was found to be the best layer material for rapid separation of amino acids (development time 10 min) using a water-in-oil microemulsion as mobile phase. The water content of the emulsion had little effect on the mobility of the amino acids.