Simultaneous determination of chromium(VI) and tungsten(VI) based on their catalytic effect on the reaction between hydrogen peroxide and iodide
Abstract
Two catalysts, which catalyse a common indicator reaction, can be determined simultaneously through a single catalytic kinetic run, if one of the catalysts is losing its catalytic activity because of an inhibition reaction. Using this principle, CrVI and WVI can be determined simultaneously based on their catalytic effect on the reaction between H2O2 and I–. Mixtures of CrVI in the range 0.015–0.3 mg l–1 and WVI in the range 0.005–0.1 ng l–1 were determined. The reason for the loss of the catalytic activity of CrVI was investigated in detail.