High-speed simultaneous ion-exclusion/cation-exchange chromatography of anions and cations on a weakly acidic cation-exchange resin column

The simultaneous ion-exclusion/cation-exchange separation column packed with a polymethacrylate-based weakly acidic cation-exchange resin of 3 μm particle size was used to achieve the simultaneous high-speed separation of anions and cations (Cl−, NO3−, SO42−, Na+, K+, NH4+, Ca2+ and Mg2+) commonly found in environmental samples. The high-speed simultaneous separation is based on a combination of the ion-exclusion mechanism for the anions and the cation-exchange mechanism for cations. The complete separation of the anions and cations was achieved in 5 min by elution with 15 mM tartaric acid–2.5 mM 18-crown-6 at a flow-rate of 1.5 ml/min. Detection limits at S/N=3 ranged from 0.36 to 0.68 μM for anions and 0.63–0.99 μM for cations. This method has been applied to the simultaneous determination of anions and cations in several environmental waters with satisfactory results.