Kinetic spectrophotometric determination of iron based on catalytic oxidation of p-acetylarsenazo

A novel catalytic kinetic spectrophotometric method for the determination of iron is developed based on the catalytic effect of Fe(III) on the oxidation reaction of p-acetylarsenazo(ASApA) by potassium periodate. Maximum absorbance of the Fe(III) ASApA KIO4 system in 8.0 × 10-3 M sulfuric acid occurs at the wavelength of 540 nm. The change in absorbance (ΔA) is linearly related with the concentration of iron(III) in the range of 0.10 4.0 ng/mL and fitted the equation: ΔA = 4.91 × 10-2 C (C: ng/mL) + 0.017, with a regression coefficient of 0.9966 at the wavelength. The detection limit of the method is 0.031 ng/mL. The relative standard deviation of the method was from 1.34% to 1.78% for 11 replicate determinations. The standard addition recovery of the method ranged from 95.71% to 103.3%. The method was used to determine iron in the black gingili paste, oat slice, sleeve-fish silk food samples. The determined results were in agreement with those by atomic absorption spectrometry.