Fe(Ⅲ)-KIO_4-胭脂红体系催化动力学单扫描示波极谱法测定痕量铁的研究

Catalytic Kinetic Oscillopolarographic Determination of Trace Fe(Ⅲ) with Fe(Ⅲ)-KIO_4-Azocarmine System

本文研究了在H2SO4介质中，痕量Fe（Ⅲ）催化KIO4氧化胭脂红的褪色反应；提出了催化动力学单扫描示波极谱法测定痕量铁的一种新方法。在1．6×10^-3mol／L H2SO4介质中，胭脂红在汞电极上产生一个还原峰，峰电位为-0．102V（vs．SCE）。当氧化剂KIO4存在时，在-0．102V处的峰电流的降低与加入Fe（Ⅲ）的含量在0～0．025μg／mL范围内呈良好的线性关系，检出限可达1．05×10^-10μg／mL。应用本法测定了蕨菜、黄芪中铁的含量，结果令人满意。

It was found that trace iron（ Ⅲ ） could catalyze the oxidation of azocarmine by KIO4 in H2SO4 medium. Based on this result, a new catalytic kinetic polarography method was proposed for the determination of trace iron（Ⅲ）. In the 0. 016 mol/L H2SO4 solution, azocarmine had a well shaped polarography reduction wave at -0. 102 V（vs. SCE）. When KIO4 was added, the peak current of the -0. 102 V（vs. SCE）was proportional to the concentration of Fe（Ⅲ ） in the range of 0-0. 025 μg/mL, and the detection limit was 1. 05 ×10^-10μg/mL. The developed method has been applied to determine trace Fe（Ⅲ） in fern and astragali with satisfactory rerults.