Fe(III)-H_2O_2-Malachite Green System for Catalytic Spectrophotometric Determination of Trace Iron

A kinetic spectrophotometric method for the determination of trace Fe(Ⅲ) has been deve_loped. It is based on the discoloring oxidation reaction between malachite green and hydrogen peroxide catalyzed by Fe(Ⅲ) in the medium of HCl solution. The linear determination range is between 0 and 48μg/L of Fe(Ⅲ). A detection limit of 0.61 μg/L is achieved. The apparent activation energy of the catalytic reaction is 37.94 kJ·mol-1. The method has been applied to the determination of iron in water samples with satisfactory results.