Simultaneous Determination of Iodide and Iodate in Seawater by Capillary Zone Electrophoresis

Abstract

We proposed a novel capillary zone electrophoresis (CZE) method with artificial seawater (pH 7.9) as the background electrolyte (BGE) for simultaneous determination of iodide and iodatein seawater. Transient isotachophoresis (ITP) with phosphate as the terminating ion was used as anon-line concentration procedure. The effective mobility of iodide was decreased by the addition of 20 m mol/l cetyltrimethylammonium chloride (CATC) to an artificial seawater BGE so that transient ITP functioned for bothiodide and iodate. Limits of detection (LODs) for iodide and iodate were 4.0 and 5.0 μg/l (as iodine), respectively. The LODs were obtained at a signal-to-noise ratio (S/N) of three. Values of the relative standard deviation (RSD) of migration time, peak area, and peak height for iodide (0.05 mg/1, n=8) were 0.6, 4.2, and 3.6%, respectively. The RSDs of migration time, peak area, and peak height for iodate (0.05 mg/l, n=8) were 0.3, 8.4, and 6.2%, respectively. The proposed method was applied to the simultaneous determination of iodide and iodate in seawater collected around Osaka Bay. A sufficient recovery percentage was obtained for iodide (87-112%) and iodate (93-112%) in the standard additional experiments.