Determination of Trace Palladium(II) by Catalytic Kinetic Spectrophotometry with Dimethyl Yellow

Based on the catalytic effects of palladium(Ⅱ) on the oxidation reactions of Dimethyl Yellow by KIO 4 in the H 2SO 4 medium, a new catalytic spectrophotometric method has been developed for the determinations of palladium(Ⅱ). The good linear relationship has been obtained in the concentration range of Pa(Ⅱ) over 0.0~6.0 μg/25 mL with a detection limit of 2.19×10 -3 μg/mL. The relative standard deviation for the determination of Pa(Ⅱ)at the concentration of 3.0 μg/25 mL was calculated as 0.78% (n=11). The results obtained from the studies on the kinetic parameters suggested that the catalytic reaction is first order and the apparent activation energy of this reaction is 67.21 kJ/mol. The method has been successfully applied to the determination of palladium in catalysts with the recovery over 99.5%~104.1%.