Simultaneous Determination of Molybdenum and Tungsten with a Kinetic Method Compensated by Synergistic Catalytic Coefficient
He Ronghuan; Wang Jianhua (Yantai Normal College,Yantai 264000)
The synergistic catalytic effect of molybdenum(Ⅵ)and tungsten(Ⅵ)on the hydrogen peroxide-iodide kinetic reaction systems has been studied by using I3-starch complex as indicator with stopped flow-FIA technique.The degree of synergistic effect was expressed by the proposed concept of synergistic catalytic coefficient D. The deviations from additivity of absorbance beyond given concentration ranges could be compensated by introducing the synergistic coefficient into the sim ul-taneous determination of a multiple mixture with the stopped flow -FIA method. The linear concentration ranges could be enlarged by compensating, which are 0 ～1.1μg/ ml for Mo(Ⅵ) and 0 ～2. 0 μg / ml for W(Ⅵ),respectively;while those are 0～0.6μg/ ml for Mo(Ⅵ ) and 0-0.8μg/ ml for W(Ⅵ),respectively,without being compensated, and the sensitivities also have been improved.Molybdenum and tungsten content in steel and simulated samples were determined, the recoveries and the relative standard deviations (RSD ) were 97.3%～102.8% and 2.1% ～2.9%for molybdenum, 96.5% ～102.1% and 2.3% ～3.4% for tungsten,respectively.