Abstract: A method was developed on a monolithic column for the fast determination of trace iodate (IO~3) by ion-pair chromatography with direct conductivity detection. The analytes were separated using a mobile phase of tetrabutylammonium hydroxide (TBA)-phthalic acid-acetonitrile on a reversed-phase silica-based monolithic column. The effects of eluent, flow rate and column temperature on the retention of iodate were investigated. The optimized chromatographic conditions for the determination of the anion were as follows: 0.25 mmol/L TBA-0.18 mmol/L phthalic acid-3% acetonitrile (pH 5.5) as mobile phase, a flow rate of 4.0 mL/min and a column temperature of 30 ℃. Under the optimal conditions, retention time of iodate was less than 0.5 min and the baseline separation of iodate was achieved without any interference by other anions (Cl~, NO~3, SO2~4, I~). The detection limit (S/N=3) was 0.36 mg/L for IO~3. Relative standard deviation (RSD, n=5) of chromatographic peak area and retention time were 0.35% and 0.28%, respectively. The proposed method was applied to the determination of trace iodate in iodized medicine. The spiked recovery of iodate was 96.4%. The method is rapid, simple, accurate, reliable, and practical.

Key words: broth, free amino acids, high performance liquid chromatography (HPLC), pork, pre-column derivatization