Kinetic-Photometric Determination of Iodide Based on Its Inhibitory Effect on The Bromate Oxidation of Indigo Carmine in Micellar Medium

Abstract

A new, simple, sensitive and selective kinetic spectrophotometric method was developed for the determination of ultra trace amounts of iodide over the range of 0.060-0.20 μg/mL.The method is based on the inhibitory effect of iodide on the oxidation of indigo carmine by bromate in acidic and micellar medium. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of indigo carmine at 612 nm with a fixed-time 0.5-2.0 min from initiation of the reaction. The relative standard deviation of 0.08 and 0.1 μg/mL iodide was 1.7 and 2.3 %, respectively. The method was applied to the determination of iodide in water.