Stationary-Phase Complexation of Crown Ethers with Polyammonium Ions Chemically Bonded on Polymer Resin

Abstract

The apparent comlexation of crown ethers with polyammonium ions chemically bonded on polystyrene-divinylbenzene copolymer resin has been chromatographically studied in methanol and acetonitrile. The retention of crown ethers with chemically bonded ammonium ion resins is affected by the nature of the counteranions; the retention is enhanced with large and poorly solvated counteranions, but is reduced with small and well solvated counteranions. In the present study, the retention mechanisms are discussed based on the retention data obtained by changing various factors, such as the crown cavity sizes, the structures of the polyammonium ions, counteranions, and the molar ratios of mixed counteranions in the stationary phase. The complexation and ion-pair formation equilibria play important roles in determining the over-all retention of crown ethers.