Indirect Differential Polarographic Determination of Trace Iron

Fe(Ⅲ) has strong effect on the photocatalytic oxidation of methyl violet in dilute sulfuric acid medium. The irradiation source was an UV lamp, and oxalic acid was used as the activator. The photochemicl oxidation product of methyl violet exhibits a 2.5 order differential palarographic wave at -0.70V vs. SCE. So this ware was chosen as an indicator for the oxidation reaction. On this ground, a novel photochemical-voltammetric method for the indirect determination of 6～300 μg/L Fe in tea samples was established. The detection limit was 3 μ g/L Fe.