This study describes inorganic anions using a column packed with a diol-modified silica gel stationary phase (diol-silica; TSKgel OH-120). In an acid eluent, such as tartaric acid or malic acid, the elution order of the analyte anions in ion chromatography using a diol-silica column was comparable to that using conventional anion-exchange columns, except for the fluoride ion. Fluoride ion would be strongly retained onto the silica gel, which is a support to fix diol functional groups. The retentions for anions was found to be enhanced by H+ in the eluent. This might electrostatically interact anions by protons retained onto diol functional groups in the column. Furthermore, the retention time of sulfate ion, which is a divalent strong acid anion, was largely reduced with increases of the column temperature up to 80 °C, while nitrite ion was slightly increased. The increase of the retention time of the nitrite ion was considered because of oxidization with elution of acidic eluent at a higher column temperature than 70 °C. The anion separation the by diol-silica stationary phase under acidic elution conditions was expected to be an ion-dipole interaction with the eluent ion and/or an electrostatic interaction with the stationary phase.
