Retention of inorganic anions using mesoporous zirconia spheres modified with anion-exchange groups as the stationary phase for ion chromatography

Abstract

A zirconia (ZrO₂) stationary phase with a chemically fixed silane coupling agent (trimethyl [3-(trimethoxysilyl)propyl]ammonium chloride; TMA), which possesses quaternary ammonium functional groups, is evaluated as a separation column for ion chromatography (IC) of anions. The selectivity for anions varies depending on the amount of TMA immobilized on the ZrO₂. The TMA-ZrO₂, with an anion-exchange capacity of 17 ± 3 µeq/g, shows an anion-exchange reaction that involves the specific retention of fluoride ion on ZrO₂. The TMA-ZrO₂ exhibits a decrease of the anion resolution with an increase of the eluent pH and an enhancement of the selective separation of fluoride ion with an increase of the column temperature. Through this study, the TMA-ZrO₂ stationary phase shows potential as a new medium for ion separation.

Keywords: Anion separation; Ion chromatography; Resolution; Temperature; Zirconia.