COMPLEXATION OF POLYETHERS IN CATION-EXCHANGE RESIN AND APPLICATION TO CHROMATOGRAPHIC DETERMINATION OF COMPLEXATION CONSTANTS IN SOLUTION

The complex formation of crown ethers with counterions in cation-excha nge resin is chromatographically evaluated with a model based on the P oisson-Boltzmann-Gouy-Chapman-Stern theory. In the model, two contribu tions are taken into account to explain distribution ratios (or chroma tographic capacity factors) of crown ethers; one is the ion-pair forma tion of a cation-crown ether complex with a sulfonate group chemically bonded on silica gel, and the other is the accumulation of cationic c omplexes in the diffuse layer. To describe this system, at least three equilibrium constants are necessary; a complex formation constant and two ion-pair formation constants between a cation-exchange site and a countercation and between a cation-exchange site and a cation complex ed by a crown ether. The combination of two chromatographic methods, i .e. the crown ether retention and the retention of a:probe cation unde r effects of the crown ether complexation with eluent cations, allows quantitative evaluation of equilibrium constants necessary for numeric al calculation. Thus, crown ethers can probe the equilibria not evalua ted by other approaches. The results of the calculation are used for t he evaluation of the validity of a simple equation previously reported for the chromatographic determination of the complex formation consta nts of:polyethers in solution.