Sequential-injection procedure for determination of iodide in pharmaceutical and drinking water samples by catalytic reaction with spectrophotometricdetection

A novel sequential-injection system was developed for determination of iodi de at very low concentrations by using a kinetic method. The method is base d on the catalytic effect of iodide on the redox reaction between Ce4+ and As3+ first described by Sandell and Kolthoff. The calibration curve is cons tructed by measuring the decrease of Ce4+ absorbance versus iodide concentr ation with a delay time of 30 s. The detection limit is 1.5 mug/L, the work ing temperature is 45 degreesC, and the working range is 0.002-0.5 mg/L. Re asonable agreement was obtained when the method was applied to pharmaceutic al and drinking water samples. The method has a sample throughput of approx imately 15/h.