Potentiometric flow-injection determination of iodide and iodine

A potentiometric flow-injection system is described, in which iodide in the concentration range 10 −6–10 −1 M may be determined at rates of up to 360 samples/hr at a flow-rate of 17.8 ml/min. Iodine, after on-line reduction to iodide with 0.1 M sodium metabisulphite, can also be determined, with a throughput of 60 samples/hr for 10 −5–10 −3 M iodine. Analyses of two pharmaceutical preparations for iodide and iodine are reported, and the results are in reasonable agreement with titrimetric values.