Abstract: Portions of 100 µL of iodide solutions containing 100 mM bromide, thiocyanate and thiosulfate as interferents were injected into carrier and reagent streams (total flow 6.6 ml/min) of 1 µM-KI and 100 mM KNO3, and iodide detected using a variety of purpose made AgI/Ag2S (details given) and commercially available iodide, sulfide and cadmium ISE. Calibration graphs of the respective ISE responses are presented. Most sensors showed good analytical performance, excepting that prepared from a 3:1 AgI/Ag2S membrane.

Abstract: Bromide, thiocyanate and thiosulfate were studied as three moderately-interfering species. The flow injection (FI) manifold was as described earlier (Pure Appl. Chem, 1976, 48, 129). Potentiometric measurements were made with an Orion Research Model 710A digital pH/mV meter and the Orion 94-06A iodide ISE was used for most of the FI work. Neutral and acidified iodate and bromate oxidant streams increased the selectivity of the iodide electrode towards the interferents. Use of ascorbic acid or metabisulfite reducing streams resulted in a greater degree of selectivity towards iodide than was obtained with either of the neutral oxidant streams but a lower degree of selectivity than was obtained when a simple nitrate reagent stream was present. Thiosulfate damaged the surface of the electrode irreparably, with a concomitant excessive peak broadening in the FI experiment and very poor baseline recovery.