Indirect A AS Determination of Iodide at the 10^-7 mol l^-1 Level by Distillation of Iodine Followed by Its Reaction with Arsenic(III)

Abstract

A new indirect method for the determination of iodide at the 10^-7 mol l^-1 level based on the reaction of distilled t with As(III) followed by the determination of the excess As(III) with hydride generation AAS is proposed. Iodide is oxidized to iodine by Ce(IV), distilled with a nitrogen carrier gas and absorbed in a KI solution. Absorbed iodine reacts quantitatively with excess As(III) in a slightly alkaline solution at 80–90° C. After the reaction iodide in the solution is removed as an Agl precipitate. The amount of distilled iodine can be determined indirectly by measuring the atomic absorbance of As by a hydride-generation technique. The calibration curve is linear over the range from 2.5×10^-8 mol l-¹ to 2×10^-7 mol l^-1, and the relative standard deviation is 2.9% (n =7 for 1×10^-7 mol l^-1 iodide.