Ion chromatographic analysis of hydronium ion using ODS modified with dodecylsulfate as the stationary phase

Abstract

The hydronium ion (H₃O⁺), the most essential species to every field of chemistry, was successfully separated from other cations. This major goal was achieved by a HPLC approach in which a reversed-phase ODS which had been initially modified with dodecylsulfate was used as the stationary phase and an aqueous KNO₃ solution was used as the mobile phase. Of all tested monovalent cations (analyte ions), the hydronium ion (H₃O⁺) showed the highest affinity towards the stationary phase, followed by NH₄⁺, Na⁺, and then Li⁺. The hydronium ion, after the separation, was directly detected using conductivity and the detection signal (conductivity) was in linear proportion (linear range 7.8 ×10⁻⁴–0.45 M; injection volume, 100 μL) to the concentration of the acid species of the tested sample. This proposed HPLC method was applicable to separate/detect H₃O⁺ from both strong and weak acidic samples.