Abstract：In this paper, a new synergetic extraction catalytic spectrophotometric method for the determination of trace chromium was studied. The method is based on the iron(Ⅲ) and chromium(Ⅵ) synergetic 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 were controlled by extraction equilibrium. The absorbance of organic phase was measured at 424 nm. The linear range of the method is 0.001 0-0.90 mg·L-1. The detection limit for chromium(Ⅵ) is 5.0×10-6 g·L-1. The relative standard deviation (n=11) for 0.20 μg·mL-1 level of Cr(Ⅵ) is 2.0%. The method has been applied to the determination of chromium in tap water and waste water with satisfactory results.
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