分光光度法测定饮料中色素含量

采用紫外分光光度法对饮料中两种食用色素进行了同时测定。确定了各色素的最大吸收波长及最大吸收波长处的吸收系数和摩尔吸收系数。结果表明柠檬黄最大吸收波长分别为424 nm,吸收系数为32.22 L.g-1.cm-1,摩尔吸收系数为1.72×104L.mol-1.cm-1;胭脂红的最大吸收波长为507 nm,吸收系数为35.92 L.g-1.cm-1,摩尔吸收系数为2.17×104L.mol-1.cm-1。测定饮料中柠檬黄和胭脂红的含量分别为4.32×10-3mg.mL-1、3.36×10-3mg.mL-1,相对标准偏差分别为2.89%、2.57%,加标回收率分别为89.7%、90.6%。该方法操作简便,易于推广,可用于实际样品的检测。

Determination of Pigments in Beverage by Ultraviolet Spectrophotometry

A method for simultaneous determination of two pigments in beverage are developed by Ultraviolet spectrophotometry.Tartrazine and ponceau 4R in beverage is determinated by this method.The results show that maximum absorption wavelengths are 424 nm and 507 nm respectively,the absorption coefficients are 32.22 L·g-1·cm-1 and 35.92 L·g-1·cm-1 respectively,the molar absorption coefficients are 1.72×104 L·mol-1·cm-1 and 2.17×104 L·mol-1·cm-1 respectively.The contents of tartrazine and ponceau 4R in beverage are 4.32×10-3 mg·mL-1 and 3.36×10-3mg·mL-1 respectively,relative standard deviations are 2.89% and 2.57% respectively,the recovery rates are 89.7% and 90.6% respectively.This method is proved to be simply and convenient and deserved to be popularized.