High-performance thin-layer chromatography of nitrogen compounds on layers of RP-18 and SIL C 18-50 untreated or impregnated with dodecylbenzenesulphonic acid and on ammonium tungstophosphate

Abstract

The chromatographic characteristics of amino acids, peprides, amino sugars, aliphatic mono- and polyamines on ready-for-use plates of RP-18 and SIL C 18-50 untreated or impregnated with dodecylbenzensulphonic acid and on layers of ammonium and tetramethylammonium tungstophosphate have been investigated using water-alcohol mixtures at different pH and ionic strengths or aqueous solutions of nitric acid, ammonium nitrate and tetramethylammonium bromide as eluents. On plates of silanized silica gel impregnated with the anionic detergent, the retention of peptides is governed chiefly by an ion-exchange mechanism. On ammonium tungstophosphate (AWP) layers, the retention of aliphatic diamines and peptides increases with increasing distance between the two —NH + 3 groups or the —NH + 3 group and the carboxylic group. For these reasons the AWP layers allow the separation of several nitrogen-containing compounds which exhibit similar chromatographic behaviour on RP-18 and SIL C 18-50 plates.