Lateral relocation in thin-layer chromatography

Abstract

In our earlier studies on the retention fundamentals in thin-layer chromatography (TLC), we have focused our attention on the important issue which was the deviation from linearity (i.e., handedness) of the chiral analytes’ migration tracks. Presently, this issue is revisited and referred to as lateral relocation of the analytes. We provide new experimental evidence of this striking phenomenon, and as a test mixture, we use (±)-2-phenylpropionic acid. Moreover, we employ three different chromatographic systems, i.e., those based on the bare silica gel layers, and the silica gel layers impregnated with l-arginine and dl-arginine. The observed lateral relocation of the 2-phenylpropionic acid enantiomers is interpreted as a non-linear motion, resembling that of the propeller-like chiral rotors. More general comments are made on lateral relocation and skewed retention of the structurally fit analytes in certain chromatographic systems.