Spectrophotometric determination of iron in silicon iron with dibromo-p-nitro-chlorophosphonazo

The color reaction between dibromo-p-nitro-chlorophosphonazo and iron could occur in 0.072 mol/L hydrochloric acid medium,forming a complex(2∶1)which had maximum absorption at 610 nm.Beer's law was obeyed for iron in the range of 0.14-0.80 μg/mL.The apparent molar absorptivity of the complex was 1.63×104 L·mol-1·cm-1.The proposed method was applied to the determination of iron in standard silicon iron sample,and the results were consistent with the certified values,giving RSD(n=6) of 1.4 %-2.1 %.