The Determination of Trace Iron(III) Using the Catalytic Spectrophotometry of Arsenazo(I)

The catalytic spectrophotometric method for the determination of trace Fe(Ⅲ) is studied based on the catalytic effect of Fe(Ⅲ) on the oxidation of arsenazo Ⅰ with hydrogen peroxide.The optimum conditions are studied.Buffer medium is acetic acid-sodium acetate(pH=4.4).The linear range for the determination of iron(Ⅲ) is 0.02～0.2μg/25mL under the reaction condition of 85℃ for 12min,and the detection limit is 1.91×10-8g/mL.The apparent activation energy Ea is 48.44kJ/mol,and the apparent reaction rate constant is 1.33×10-3 mol·L-1·s-1.The method was applied to determination of trace iron in rice sample,hair sample.The relative standard deviations(RSD) are 2.47% and 3.70%,and the recoveries are 92.5%～97.4%.