Catalytic kinetic spectrophotometric determination of trace iridium (IV) in potassium periodate-xylenecyanol FF system

On the basis of catalytic action of iridium (IV) on the oxidation reaction of xylene cyanol FF by the potassium periodate in the medium of 0.02 mol/L H2SO4 and heating at 95°C, a new catalytic kinetic spectrophotometry for the determination of iridium (IV) is established. The experiment results show that this reaction is first-order kinetic one. Under the optimal conditions, the linear scope is 0.287-4.00 μg/L for iridium and detection limit is 1.828 × 10-11 g/L iridium at the wavelength of 615 nm. The rate constant of this reaction is 1.715 × 10-3/s, and the activated energy of the reaction is 71.00 kJ/mol. The method has been used to the determination of trace amounts of iridium (IV) in the molecular sieve catalyst and activated carbon with the recovery of 96.0%-107.4% and the results are consistent with those obtained by atomic absorption spectrometry.