Flow injection determination of oxidants with leuco-thionine blue

Abstract

The application of leuco-thionine blue (LTB) as a reducing agent in flow injection analysis is described. Results for the determination of periodate, chromate, vanadate and hexacyanoferrate(III) are presented. With spectrophotometric detection, based on the absorption of thionine blue at 670 nm, the limits of determination were of the order of 10^–5 mol l^–1. The proposed method has been applied to the resolution of Cr^VI-Cr^III mixtures and to the determination of both chromium and vanadium in steels, vanadium in petroleum products and hexacyanoferrate(III) in photographic solutions.