Determination of iodide ion in impregnated charcoals by flow injection

Abstract

A procedure for the determination of iodide in charcoals impregnated with potassium iodide is described. An aqueous extract is prepared and the iodide ion concentration in this extract (up to 4 × 10–3 mol dm–3) is determined by injection into a water stream that is merged with an aqueous solution containing potassium iodate and sulfuric acid, followed by absorptiometric measurement at 460 nm. The analysis is simple and rapid, with a limit of detection of 6 × 10–5 mol dm–3 iodide and a relative standard deviation (n= 10) of 1.2% for 1 × 10–3 mol dm–3 iodide. The procedure was used to measure the levels and the distribution of potassium iodide in impregnated charcoals. The flow method is discussed with reference to the chemistry of elementary iodine in aqueous solution.