High-Performance Thin-Layer Chromatography and Pressurized Planar Electrochromatography of Some Diastereomeric Amino Acid Derivatives in Reversed-Phase System with Carboxylic Acid Mobile Phase Buffers

The separation of 1-fluoro-2,4-dinitrophenyl-5-L-valine amide (FVDA) diastereomeric derivatives of aspartic acid, cysteine, and histidine by means of high-performance thin-layer chromatography (HPTLC) as well as pressurized planar electrochromatography (PPEC) techniques in systems with HPTLC RP-18W plates and the various acetonitrile-buffer mobile phases is presented. The influence of the mobile phase components, i. e., acetonitrile concentration and buffer kind on migration distance of the solute zones, was investigated. The effect of mono (formic) and various dicarboxylic acids (oxalic, malonic, maleic, malic, succinic, tartaric, and pimelic) as the mobile phase buffer components on the solute retention was studied. It is observed that an increase of acetonitrile content of the mobile phase affects the solute zone migration and retention in PPEC and HPTLC. What is more, the separation selectivity in the latter and former techniques differs. The PPEC mode presents a higher efficiency in comparison with HPTLC. The solute separation with electromigrational system is more fragile on the kind of acid used as mobile phase buffer component than with chromatographic method. Nevertheless, the influence of the kind of mobile phase buffer component on solute selectivity and retention in both techniques was determined. The electrokinetic (zeta) potential of the stationary-mobile phase interface was measured and compared with the solute retention data of both techniques.