Determination of Inorganic Anions in Seawater Samples by Ion Chromatography with Ultraviolet Detection Using Monolithic Octadecylsilyl Columns Coated with Dodecylammonium Cation.

A fast and sensitive ion chromatographic method for the simultaneous determinations of six inorganic anions [iodate (IO), bromate (BrO), bromide (Br), nitrite (NO), nitrate (NO), and iodide (I)] in seawater is described using dodecylammonium (DA)-coated monolithic octadecylsilyl (ODS) columns, a concentrated aqueous NaCl mobile phase containing dodecylammonium chloride (DAC), and a UV detector. The DA-coated monolithic ODS columns show greater retention for iodate and weaker retention for iodide, compared to dilauryldimethylammonium (DDA)-coated monolithic ODS columns. Six anions were determined within 12 min with baseline separation without interferences by matrix ions, such as Cl and SO, in seawater, compared to a DA-coated particulate ODS column (it took 25 min per sample) obtained previously.