茜素红S催化动力学光度法测定痕量铁(Ⅲ)及反应机理探讨  

Catalytic Kinetic Spectrophotometric Determination of Trace Iron (Ⅲ)Based on the Decoloration Reaction of Hydrogen Peroxide and Alizarin S

作　　者：陈贤光[1] 邹小勇[1] 梁起[1] 欧阳良琪[1] 陈国荣[1] 李泽之[1] 钱莹[1] 

机构地区：[1]中山大学化学与化学工程学院,广州510275

出　　处：《分析化学》2006年第3期371-374,共4页Chinese Journal of Analytical Chemistry

基　　金：国家自然科学基金资助项目(No.20475068);广东省自然科学基金资助项目(No.031577);中山大学学生科研项目。

摘　　要：在pH 4.5的NaAc-HAc缓冲介质中,以邻菲咯啉（phen）作活化剂,痕量Fe（Ⅲ）对H2O2氧化茜素红S（ARS）的褪色反应存在明显的催化作用,由此建立了测定痕量铁（Ⅲ）的催化动力学光度法.采用固定时间法,在λmax=422 nm处,对催化体系和非催化体系进行光度测定,应用了正交试验法确定最佳条件,测定了有关动力学参数.该方法的检出限为0.63μg/L;线性范围为0～20μg/L,应用于一次蒸馏水、分析纯盐酸中痕量铁的测定,结果令人满意.提出了Fe（Ⅲ）-ARS-phen三元络合物活性中间体的催化反应机理设想,并推测催化反应经历了羟自由基氧化反应的历程.A new catalytic kinetic spectrophotometric method was studied for the determination of trace iron （Ⅲ） based on the remarkable catalytic effect of iron（Ⅲ ） on the oxidation of alizarin S （ARS） by hydrogen peroxide with 1,10-phenanthroline （phen） as activating agent in HAc-NaAc buffer solution （ pH 4.5 ）. Indicator reaction is followed spectrophotometrically by measuring the absorbance change at λmax=422 nm and constant temperature （87℃±0.5℃） by fixed time method. Experimental conditions were optimized by orthogonal test and the kinetic parameters were calculated. The detection limit is 0.63μg/L, and the linear range is 0 -20μg/L. The method has been successfully applied to the determination of trace iron （Ⅲ） in distilled water and analytical pure hydrochloric acid. The mechanism of this reaction was deemed to. form a mixed-ligand complex with the formation of Fe（Ⅲ） （phen） （ARS）2. And the catalytic oxidation reaction was considered as a radical reaction of hydroxyl radicals.

关 键 词：动力学光度法 铁(Ⅲ) 茜素红S 反应机理 

分 类 号：O657.3[理学—分析化学] O614.811[理学—化学]