碘离子选择电极检测催化动力学分析法测定抗坏血酸

Catalytic Kinetic Determination of Trace Amount of Ascorbic Acid with Iodide ion selective electrode

在稀硫酸介质中，痕量去氢抗坏血酸对Ｖ（Ｖ）－ＢｒＯ－３－Ｉ－反应有强烈的催化作用，体系中Ｉ－浓度的变化可借碘离子选择电极跟踪检测．据此，本文建立了测定６×１０－７～２×１０－５ｍｏｌ／Ｌ抗坏血酸的催化动力新分析法。

The experiments show that dehydroascorbic acid has very strong activation effect on the slow catalytic redox reaction between bromate and iodide in pH 2.0 sulphuric acid medium at 30 C o. The changes in concentration of iodide ion in the system can be monitored by means of iodide ion Selective electrode. The influencc of the concentration, reaction temperature and foreign substances on the catalytic kinetic determination of ascorbic acid has been examined. A detection limit of 3×10 -7 mol/L and calibration graph from 6×10 -7 to 2×10 -5 mol/L ascorbic acid are obtained by the rate procedure. Ascorbic acid in vitamine C injection liquid and tomato juice was analysed by this method, with satisfactory results.