溴酸钾-甲基百里酚蓝体系阻抑动力学光度法测定痕量乙二胺四乙酸(EDTA)  

Determination of trace EDTA by inhibition kinetic-spectrophotometry in KBrO_3-Methyl thymol blue system

作　　者：陈伟 王胜 王培娟 王树勋 钟庆红 程清模 

机构地区：[1]烟台经济技术开发区疾病预防控制中心,烟台264006

出　　处：《中国食品添加剂》2008年第5期153-155,共3页China Food Additives

摘　　要：在稀硫酸介质中，Fe（Ⅲ）催化溴酸钾氧化甲基百里酚蓝褪色的反应可被微量乙二胺四乙酸（ED-TA）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。采用单因素法对影响方法的7个因素进行了优化，得到了最佳实验条件为：氧化剂溴酸钾溶液用量为3.5mL，还原剂甲基百里酚蓝溶液的用量为2.5mL，催化剂Fe（Ⅲ）标准溶液用量为0.12mL，催化反应介质为0.1mol/L硫酸溶液3.0mL，反应在90℃水浴中加热8.0min，0.4mg/mL的EDTA0.2mL为终止剂。该方法用固定时间法在445nm波长处监测阻抑反应。方法的线性范围为0-50.0μg/50mL，检出限为2.1×10^-6mg/mL，标准加入回收率为95%-98%。该方法用于罐头等食品中EDTA的测定，获得满意结果。In the sulfuric acid solution, the catalytic action of Fe （ Ⅲ ） on the oxidation of methyl thymol blue by KBrO3 was effectively inhibited by ethylenediaminetetraacetic acid （EDTA）. The reaction was effectively stopped by superfluous EDTA. The single factor methods were used to optimize the factors which have the possibility to affect the determination method. The optimum experimental conditions were selected as followed： KBrO3 was used as the oxidant and the amount of it was 3.5 mL, the methyl thymol blue was used as the reductant whose amount was 2. 5 mL, Fe （ Ⅲ ） was used as the catalyst whose amount was 0. 12 mL, the catalytic reaction happened in the sulfuric acid solution at 90° C in the water bath for 8. 0 min, and then 0. 4 mg/mL EDTA 0. 2 mL was added into the reaction system to make the reaction stopped immediately. The decrease in absorbance was measured at 445 mn by UV at fixed time intervals. The linear determination range is between 0 and 50. 0 μg/50 mL of EDTA. A detection limit of 2. 1 × 10 - 6 mg/mL is achieved. The recoveries are 95% -98%. The method can be applied to the determination of trace EDTA in canned food with satisfactory results.

关 键 词：动力学光度法 乙二胺四乙酸(EDTA) 溴邻苯三酚红 H2O2 

分 类 号：TS207.3[轻工技术与工程—食品科学]