硫酸-H2O2-罗丹明B-体系阻抑动力学光度法测定痕量EDTA的研究

研究阻抑动力学光度法测定痕量EDTA的新体系。在硫酸介质中,Fe（Ⅲ）催化H2O2氧化罗丹明B的反应可被微量EDTA有效地阻抑,被过量EDTA有效的终止,据此建立了测定痕量EDTA的动力学光度法,用固定时间法在555 nm波长处监测阻抑反应。在0～45.0μg/50mL范围为,线性关系良好,回归方程为ΔA=2.25×10^-2c（c：μg/50mL）,γ=0.9991,检出限为1.1×1 0^-6mg/mL。该方法用于罐头等食品中EDTA的测定,获得满意结果。

Determination of Trace EDTA by Inhibition Kinetic-spectrophotometry in A H2SO4 H2O2-Rhodamine B System

We evaluated the use of inhibition kinetic spectrophotometry for determination of trace EDTA.In a sulfuric acid medium,the H_2O_2 oxidation of rhodamine B catalyzed by Fe3＋ is sensitive to inhibition by trace EDTA and can be blocked by excessive EDTA.We developed a new inhibition kinetic spectrophotometric method for trace EDTA determination using this principle.Absorbance at 555 nm was measured over time to monitor the inhibition of rhodamine B oxidation for the determination of EDTA.This method produced a linear range of readout for EDTA between 0-45.0μg/50 mL,the regression equationand was ΔA=2.25×10^-2 c（c：μg/50 mL）,γ=0.9991,the detection limit was 1.1×10^-6 mg/mL.The method was successfully applied to determine trace EDTA in canned food.