Simultaneous determination of anions and cations by ion-exclusion chromatography-cation-exchange chromatography with tartaric acid/18-crown-6 as eluent

Ion-exclusion chromatography-cation-exchange chromatography was developed for the simultaneous separation of common inorganic anions and cations (Cl-, NO3- and SO42-; Na+, NH4+, K+, Mg2+ and Ca2+) on a weakly acidic cation-exchange column by elution with weak acid. Generally, the resolution among these monovalent cations was only moderate, thereby hindering the determination of these analytes in natural-water samples. Therefore, 18-crown-6 was added to the eluent to improve the resolution. A good separation of these anions and cations on a weakly acidic cation-exchange column was achieved in 30 min by elution with 5 mM tartaric acid/6 mM 18-crown-6/methanol-water (7.5:92.5). The ion-exclusion chromatography-cation-exchange chromatography method developed here was successfully applied to the separation of major anions and cations in an environmental water sample. (C) 1999 Published by Elsevier Science B.V. All rights reserved.