Indirect automatic determination of iodide by flame atomic absorption spectrometry Original Research Article

A continuous flow procedure is proposed for the indirect determination of iodide based on its reducing properties. Chromium(VI) in acid medium was injected into an iodide stream, and Cr(VI) was reduced to Cr(III). This Cr(III) formed was retained on-line, proportionally to the iodide in the sample, on a poly(aminophosphonic acid) (PAPhA) chelating resin, which is selective only for this oxidation state, while non-reduced Cr(VI) was determined by flame atomic absorption spectrometry (FAAS). The proposed method allows the determination of iodide in the range 0.6–25 μg ml−1 with a relative standard deviation of 2.5% at a rate of ca. 80 samples per hour. This method has been applied to the determination of iodide in iodized table salt.