催化动力学分光光度法测定粉丝中的微量铬

摘要

A new catalytic spectrophotometric method for the determination of trace Cr (Ⅵ) was developed. It is based on the fact that Cr (Ⅵ) can catalyze the fading reaction of alizarin green with catalytic oxidation in acetic acid- sodium acetate buffer. We investigated acidity, the reaction temperature, dosage of alizarin green, hydrogen peroxide dosage and concentration, and reaction time on the influence of the reaction system in detail, determined the best catalytic bleaching conditions.Best fading wavelength was 610 nm.The detection limit for Cr (Ⅵ) was 1.41 ×10-2μg/mL.The linear range of the determination was 0.01μg/mL-0.60μg/mL.The method was applied to the determination of Cr (Ⅵ) in vermicelli (preprocessed by high-pressure closed digestion)and tap water.The results were closed to that determined by 1,5-diphenylcarbazidc spectrophothmetry. The average recovery rate were 99.8%and 98.94%,with satisfactory result.%在醋酸-醋酸钠缓冲介质中，Cr（Ⅵ）对过氧化氢氧化茜素绿褪色反应有催化作用，据此建立了茜素绿的催化动力学分光光度法测定Cr（Ⅵ）的新方法。详细考察了反应酸度、温度、茜素绿用量、过氧化氢用量及浓度以及反应时间等对反应体系的影响，确定了催化褪色反应的最佳条件。最佳测定波长为610 nm，检出限为1.41×10-2μg/mL，线性范围为0.01μg/mL～0.60μg/mL，用于粉丝和实验室自来水中Cr（Ⅵ）含量的测定，结果与二苯碳酰二肼分光光度法测定结果相近，平均回收率分别为99.8%、98.94%，结果满意。