茜素绿光度法测定酒中的微量铬

Determination of chromium by alizarin green spectrophotometry

在硫酸介质中，铬（Cr）（Ⅵ）氧化茜素绿而使溶液褪色，Cr（Ⅲ）在NaOH溶液中以H2O2氧化成Cr（Ⅵ），据此建立了茜素绿光度法同时测定Cr（Ⅲ）和Cr（Ⅵ）的新方法。详细考察了反应酸度、温度、茜素绿浓度以及反应时间等对测定的影响。最大褪色波长为610nm，表观摩尔吸光系数为8为1．13×10^4L／（mol·cm）。Cr（Ⅵ）的质量浓度在2μg／10mL-20μg／10mL范围内符合比尔定律。方法用于各种酒中Cr（Ⅲ）和Cr（Ⅵ）的测定，结果与二苯碳酰二肼光度法测定结果一致。

A new spectrophtometric method for determination of chromium （Ⅲ） and chromium （Ⅵ） simultaneously was proposed based on the decoloration of alizarin green oxidized by chromiu （Ⅵ） in the medium of sulfate solution and the reaction of chromium （Ⅲ） being oxidized by hydrogen peroxide in sodium hydroxide solution. The parameters such as acidity, reaction temperature, dosage of alizarin green and reaction time for the system were studied in details. The maximal decoleration wavelength located at 610nm with the apparent molor absorption of 1.13 × 10＆4 L/mol·cm. Beer＇s law was obeyed in the range of2μg/10ml-20 μg/10 ml for chromium （Ⅵ）. The proposed method was applied to determine the concentration of chromium （Ⅲ） and chromium （Ⅵ） in wine and the results were agreement with that determined by 1, 5-diphenylcarbazide spectrophotbmetry.