Separation of Polynuclear Aza-Heterocyclics by High-Pressure Liquid Chromatography Using a Silver-Impregnated Adsorbent

Abstract

Fast, high-efficiency liquid chromatographic separations of polynuclear aza-heterocyclic hydrocarbons were obtained with silver ion impregnated on the surface of Zipax® chromatographic packing. Between 1000 and 2000 theoretical plates per meter were generated for these compounds at velocities between 0.3 and 3.2 cm/sec. Acridine could easily be detected at the 1-ng level per injection. The compounds are separated by donor-acceptor complexing between the adsorbed silver ion and the heterocyclic nitrogen atom. The elution order can be explained on the basis of basicity and steric accessibility of the nitrogen lone-pair. There is some evidence, however, for a competing retention process, based on adsorption.