Utilization of a diol-stationary phase column in ion chromatographic separation of inorganic anions

We describe the ion chromatographic separation of inorganic anions using a diol-stationary phase column (–CH(OH)CH2OH; diol-column) without charged functional groups. Anions were separated using acidic eluent as in typical anion-exchange chromatography. The retention volumes of anions on the diol-column increased with increasing H+ concentration in the eluent. The anion-exchange capacities of diol-columns in the acidic eluent (pH 2.8) were larger than that of zwitterionic stationary phase column but smaller than that of an anion-exchange column. The separation of anions using the diol-column was strongly affected by the interaction of H+ ions with the diol-functional groups and by the types of the eluents. In particular, the selection of the eluent was very important for controlling the retention time and resolution. Good separation was obtained using a diol-column (HILIC-10) with 5 mM phthalic acid as eluent. The limits of detection at a signal-to-noise ratio of 3 ranged from 1.2 to 2.7 μM with relative standard deviations (RSD, n = 5) of 0.04–0.07% for the retention time and 0.4–2.0% for the peak areas. This method was successfully applied to the determination of H2PO4−, Cl−, and NO3− in a liquid fertilizer sample.