Kinetic-catalytic-spectrophotometric determination of low concentrations of molybdenum in white wines

The paper describes the determination of the molybdenum content in white wines based on its catalytical action on the kalium iodide oxidation by hydrogen peroxide in acid medium. The optimum reaction conditions (the catalyst, KI and H2O2 concentrations, the pH value, the order of the reagent additions, the temperature) have been found by studying the effect of the reaction variables. The influence of some metallic ions (Ca2+, Mg2+, Zn2+, Cd2+, Fe2+ and Fe3+) and complexing anions F-; C2O42-, EDTA(4-)) on the catalyzed reaction rate was elucidated. The molybdenum concentration was estimated by the tangent, fixed-time and fixed-absorbance method. The obtained average values for molybdenum content in white wines are within the 1.77x10(-7)-1.83 x 10(-7) mol l(-1) range. (C) 1999 Elsevier Science B.V. All rights reserved.