紫脲酸铵-KIO_4体系阻抑动力学光度法测定痕量EDTA

Determination of Trace EDTA by Kinetic-Spectrophotometry Inhibition in Murexide-KIO_4 System

[目的]研究阻抑动力学光度法测定痕量EDTA的新体系。[方法]2004年在冰乙酸溶液中,Fe(Ⅲ)可以催化KIO4氧化紫脲酸铵(MX)褪色,痕量EDTA可以有效地阻抑、过量EDTA可有效地终止反应,用固定时间法在520nm波长处监测阻抑反应。[结果]方法的线性关系良好,线性范围为0～45.0μg/50ml,检出限为1.8×10-6mg/ml。[结论]本方法用于罐头等食品中EDTA的测定,效果满意。

[Objective] To study a new system of determing trace EDTA by inhibition kinetic-spectrophotomttry. [Methods]In acetic acid glacial solution, Fe（ Ⅲ ） could calalyze the oxidation of murexide by KIO4 . The reaction was effectively inhibited by trace EDTA, and was effectively stopped by superfluous EDTA. The decrease in absorbance was measured at 520 nm at fixed time intervals. [Results]The linear determination range is between 0 and 45.0 μg/50 ml of EDTA. A detection limit of 1.8 × 10^-6 mg/ml is achieved. [Conclusion]This method applied to the determination of trace EDTA in canned food was satisfactory.