Redox Reaction Catalyzed by a Porous Graphite Carbon Packing and its Application to Selectivity Enhancement of High-performance Liquid Chromatography Separation of Metal Complexes

Abstract

A new HPLC method was developed for the selective separation of metal complexes by using a redox reaction as a secondary chemical equilibrium. In a study of the reversed-phase ion-pair liquid chromatography of trans-1,2-diaminocyclohexanetetraacetate (DCTA) complexes of transition metal ions, it was noted that the redox reaction between the divalent and trivalent cobalt complexes were extremely accelerated by using a porous graphite carbon (PGC) column. This finding was ascribed to the catalytic effect of the PGC. The retention of Co–DCTA complex can be modified by treating the PGC column with the eluent containing sodium sulfite. The cobalt complex was completely separated from 1000-fold molar excess of the Bi^III, Fe^III, Cu^II, and Ni^II complexes.