紫外分光光度法测定橙汁中维生素C的含量

[目的]为市售饮料中维生素C（Vc）的科学测定提供参考。[方法]利用Cu2＋催化溶解氧氧化Vc,建立紫外分光光度法测定橙汁中还原型Vc的方法,并对测定条件进行优化。[结果]采用磷酸和醋酸混酸溶液（3∶7,V∶V）作稳定剂,Cu2＋为催化剂,70℃恒温水浴中,测定市售橙汁饮品中Vc的含量,标准曲线方程为y=0.0714x＋0.1350,线性相关系数为0.9995。该方法精密度RSD（n=5）为0.35%,加标回收率为98.5%。[结论]建立了紫外分光光度法测定橙汁中Vc的方法,该方法简单、快速,结果令人满意。

Determination of Vitamin C in Orange Juice by UV Spectrophotometric Method

[Objective] The aim was to provide references for the scientific determination of Vitamin C(Vc) in sold beverage.[Method] With Cu2+ as catalyst to oxidize Vc,the method to determine reduced Vc in orange juice by UV spectrophotometry was constructed,and then the determination conditions were optimized.[Result] With the mixed solution of phosphoric acid and acetic acid(3∶7,V∶V) as the stabilizer,Cu2+ as catalyst and in the 70 ℃ water-circulator bath,Vc content in the sold orange juice was determined,the standard curve equation was y=0.071 4x+0.135 0,the linear correlation coefficient was 0.999 5,the precision RSD(n=5) was 0.35% and recovery rate was 98.5%.[Conclusion] The method to determine Vc in orange juice by UV spectrophotometry was constructed,which was simple and fast and whose results were very satisfying.