Determination of Trace Iodide in Saturated Brine Using Ion Chromatography

A new method was developed for the determination of iodide in saturated brine after in-line pretreatment by ion chromatography with pulsed amperometric detection. IonPac Cryptand C1 column was used to concentrate iodide in saturated brine sample, which was subsequently rinsed with 10 mM NaOH to remove interfering chloride. Third, NaOH at 0.5 mM concentration was used to elute iodide from the concentrator column and refocus it on the head of the AG20 guard column. The separation of iodide was achieved on an IonPac AS20 column with 25 mM NaOH as eluent. The detection limit of iodide was 0.07 μg l−1 (50 μl injection, signal-to-noise ratio of 3) and the linear range of the calibration curve of peak height vs analyte concentration was from 5.0 to 1000 μg l−1. The relative standard deviation (RSD) of the peak height for 50 μg l−1 iodide was 1.0% (n = 9).