Catalytic Kinetic Spectrophotornetric Determination of Trace Cobalt with Peroxide Hydrogen-Orange G System

A new catalytic kinetics spectrophotometic method is proposed for the determination of cobalt,based on the fact that cobalt can catalyze the discolouring reaction of orange G oxidized by hydrogen peroxide in NH3-NH4Cl buffer solution medium.Under the optimum experimental conditions,the linear range of the determination is 0.006～2.0 μg/25 mL and the detection limit of 3.41×10-3 μg/25 mL.The proposed method is applied to the determination of trace amounts of cobalt in vitamin B12 with satisfactory results.