Helical nickel(II) complexes as mobile phase additives in the reversed-phase high-performance liquid chromatographic separation of alkylamine enantiomers

Abstract

The addition of nickel(II) chelates of tetradentate Schiff bases differing slightly in molecular structure to a water–acetonitrile (80 + 20) mobile phase in reversed-phase high-performance liquid chromatography makes it possible to perform enantiomeric and diastereoisomeric separations of aliphatic mono- and diamines. The separation was achieved on an octadecylsilane stationary phase without derivatization of the starting amine, and the results were compared with those obtained by a gas chromatographic procedure. The influence of helical structure, hydrophobicity, concentration and adsorption of the chelates present in the chromatographic system on the separation of the solutes studied is discussed.