Indirect automatic determination of iodide by flame atomic absorption spectrometry

A continuous flow procedure is proposed for the indirect determination of i odide based on its reducing properties. Chromium(VI) in acid medium was inj ected into an iodide stream, and Cr(VI) was reduced to Cr(III). This Cr(III ) formed was retained on-lint, 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 mu g ml(-1) with a relative st andard 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. (C) 2000 Elsevier Science B.V. All rights reserved.