Determination of iodide and iodate in edible salt by ion chromatography with integrated amperometric detection

Iodised salt compositions formulated with potassium iodate typically have iodate content of 20–40 ppm (μg/g) which translates to iodine content of 15–30 ppm. The technique of iodide estimation in brine by ion chromatography with amperometric detection was applied to iodate estimation in salt. The method involved reduction of iodate to iodide with excess sodium bisulphite followed by estimation of iodide. No other pre-treatment was necessary for iodate estimation in the concentration range of interest for iodised salt. Quantitative analysis was feasible for iodate concentrations ⩾5 ppm in salt. Iodised salt formulations containing iodide and iodate together were also analysed and the two constituents were quantified separately. Interferences from impurities normally present in salt were insignificant. An important advantage of the present method is that it eliminates the possibility of misleading results from potential adulterants which can impart positive iodometric test while, at the same time, keeping the analytical procedure simple.