[Extraction catalytic spectrophotometric determination of trace chromium by synergetic catalytic effect]

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 0.0010-0.90 mg x L(-1). The detection limit for chromium(VI) is 5.0 x 10(-6) g x L(-1). The relative standard deviation (n = 11) for 0.20 microg x 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.