Application of ion-exclusion/cation-exchange chromatography to water quality monitoring of sub-urban river

A non-suppressed ion-exclusion/cation-exchange chromatography with conductimetric detection for the simultaneous determination of anions (SO42-, Cl-, NO3-, I-, F-, HCOO- and CH3COO-) and cations (Na+, K+, NH4+, Mg2+ and Ca2+) commonly found in a typical suburban river water and discharged water biologically treated by an activated sludge process for urban sewage was studied on a polymethacrylate-based weakly acidic cation-exchange resin column and a mixed eluent consisting Of succinic acid, tartaric acids, and 18-crown-6 at pH 2.9. The separation mechanism is based on the ion-exclusion effect for the anions and the cation-exchange effect for the cations. Under the optimized eluent conditions (26 mM succinic acid/4 mM tartaric acid/1 mM 18-crown-6 at 0.6 mL/min), the simultaneous separation of anions and cations was achieved in ca. 20 min. The analytical performances, including calibration graph, detection limit, reproducibility, and recovery tests, were evaluated under the optimized chromatographic conditions. This simple and convenient non-suppressed ion-exclusion/cation-exchange chromatographic Method Could be successfully applied for evaluating the water quality Of a sub-urban river watershed including sewage treated water, in terms of the biological oxidation reaction of NH4+ to NO3-.