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

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 x 10(-4)-0.45 M; injection volume, 100 microL) 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.