Stopped-flow determination of iodide in pharmaceutical and food samples

Abstract

The iodide-catalysed reaction between cerium(IV) and arsenic(III) has been studied using a modular stopped-flow system. The features of both the stopped-flow and conventional kinetic methods have been compared by using the same instrument. The stopped-flow method has a wider linear range and is faster than the conventional kinetic method and has been applied satisfactorily to the photometric determination of iodide in pharmaceutical preparations, table salt and cow's milk. The results obtained show that the stopped-flow method is simple, inexpensive and rapid and requires no sophisticated equipment. In addition, its high sampling rate makes it particularly suitable for the routine determination of iodide.