Differential-pulse polarographic determination of iodide in common salt

Abstract

A differential-pulse polarographic method, which does not require a separation or pre-concentration step, is described for the determination of iodide in iodide-fortified common salt. The proposed method is both rapid and precise, with a relative standard deviation for 7 p.p.m. of iodide in sodium chloride of 10.4%. The relatively low losses of iodine observed, even in an alkaline medium, can be ascribed to the oxidation of iodide to iodate. The use of a calibration graph can account for this loss and hence minimises the systematic error.