PREDICTION OF RETENTION FOR HALIDE ANIONS AND OXOANIONS IN SUPPRESSED ION CHROMATOGRAPHY USING MULTIPLE SPECIES FLUENT

The retention behavior of inorganic halide and oxoanions is studied as a function of changing eluent composition. The model developed for separation of Cl-, Br-, ClO3-, BrO3-, SeO32-, SeO42-, and PO43- ions with eluent containing HCO3-, CO32-, and OH- anions is utilized for determination of selectivity coefficients for sample and eluent species. It can also take into account the protonation of the sample ions. The model effectively characterizes the behavior of the analytes under elution conditions of practical importance. The predicted and measured retentions are in rather good agreement. The capacity factors determined for these anions make possible a reliable planning for IC separation of them with carbonate eluent in relatively wide ranges of concentration and pH. The different retention behaviors of mono-, di-, and trivalent anions as a function of pH are also interpreted in this eluent system.