Rapid determination of iodide in seawater samples by ion chromatography with chemically-bonded vitamin-U stationary phase

Abstract

A simple and rapid analytical method using a laboratory-made packed column (100mm×0.32mm i.d.) was developed for the determination of iodide in seawater. The stationary phases were prepared by the reaction of the hydroxyl group on the surface of the diol-group bonded silica gel with vitamin U. Simultaneous separation of four common inorganic anions (iodate, nitrate, iodide, and thiocyanate) was achieved within 9min using 0.05mM sulfuric acid–methanol (99:1, v/v) as the eluent. The limit of detection of iodide was 8.2μgl−1 (S/N=3), and the limit of quantification was 27μgl−1 (S/N=10). The RSD values of retention time, peak area and peak height were all smaller than 2.4%. The present analytical method was successfully applied to the rapid and direct determination of iodide in seawater samples collected from Japan coasts, and gave iodide content from 46.8 to 54.1μgl−1, by using a standard addition method. The recoveries of added iodide were from 95.6 to 106.4%. In the present system, the retention of analytes may not be caused by electrostatic interaction, but by hydrophobic interaction.