In this study, we developed a straightforward and sensitive method for the trace determination of iodide in brine used for chlor-alkali electrolysis. The method involves the oxidation of iodide to iodate and the subsequent determination of the iodate by differential pulse voltammetry. The quantitative iodide conversion to iodate is achieved by treatment with sodium hypochlorite. After 20 minutes reaction time, excess hypochlorite is removed by adding sodium sulfite. Interfering metal traces are complexed by EDTA addition. The described differential pulse voltammetric method for the determination of iodide in brine has significant advantages over other commonly employed methods. Besides the excellent price-performance ratio, the voltammetric iodide determination excels by its sensitivity, selectivity and high degree of matrix independence.
