INHIBITION-KINETIC SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF MOLYBDENUM(VI)

The color fading, oxidation of ethyl violet by hydrogen peroxide was found inhibited evidently by the presence of trace amounts of molybdenum. And the magnitude of the difference of absorbance Δ A between the inhibited color fading reaction solution ( A 1) and the non inhibited color fading reaction solution (A 2) was found to keep a linear relationship with the concentration of Mo(Ⅵ) in the range of 0 to 7.3 μg per 25 mL of solution. Absorbance measurements were made at 593 nm, which is the absorption maxima of ethyl violet. Detection limit of this reaction for Mo(Ⅳ) was found to be 3.4×10 -6 g·L -1 . Based on these findings, an inhibition kinetic photometric method for the determination of traces of Mo(Ⅵ) in vegetables was established. RSD′s of less than 3 1% and recoveries in the range of 98.2% to 102.0% were obtained in the analysis of some vegetable samples.