[Simultaneous determination of iron and molybdenum by extraction catalytic spectrophotometry].

In this paper, a new extraction catalytic spectrophotometric method for the simultaneous determination of iron and molybdenum has been studied. The method is based on the difference of the reaction rate of iron(III) and molybdenum(VI) catalyzed oxidation of o-aminophenol by hydrogen peroxide in weak acidic medium at pH 5.5. The reaction time, concentration of o-aminophenol in aqueous phase and degree of reaction are controlled by extraction equilibrium. The absorbance of organic phase is measured at 424 nm. The linear ranges of the method are 0.010-0.30 microgram.mL-1 (for iron) and 0.50-2.0 micrograms.mL-1 (for molybdenum). The method has been applied to the simultaneous determination of iron and molybdenum in soybean with satisfactory results.