摘要
高效毛细管电泳电化学检测同时测定了6种茶叶中的咖啡因、表儿茶素和抗坏血酸的含量，考察了实验参数对分离、检测的影响。在最佳实验条件下，以300 靘直径的碳圆盘电极为检测电极，检测电极为1.20 V(vs.SCE)，在25 mmol/L硼酸盐25 mmol/L磷酸盐(pH 7.6)的混合运行缓冲液中，上述各组分在16 min内能完全分离。咖啡因、表儿茶素和抗坏血酸在2×10-3mol/L～１×10-5 mol/L、5×10-5mol/L～5×10-7mol/L、2×10-4 mol/L～1×10-5mol/L范围内呈线性关系，检测下限分别为6×10-6mol/L、4×10-7mol/L和1×10-6mol/L。该法直接用于茶叶中咖啡因、表儿茶素和抗坏血酸的测定，结果令人满意。
A simultaneous determination of caffein, (-)-epicatechin and ascorbic acid in tea samples by capillary zone electrophoresis with electrochemical detection (CE-ED) is reported. The effect of potential applied to the working electrode, pH and concentration of running buffer, separation voltage and injection time on CE-ED was investigated. Under the optimum conditions, these three analytes can be separated in a 25 mmol/L borax-phosphate runing buffer (pH 7.6) within 10 min. A 300 mum diameter carbon disk electrode was used as the working electrode positioned carefully opposite the outlet of the capillary in a wall-jet configuration at potential of 1.20 V (vs. SCE). Good linear relationship was established between peak current and concentration of analytes in the range of 2 x 10(-3) mol/L similar to 1 x 10(-5) mol/L for caffein, 5 x 10(-5) mol/L similar to 5 x 10(-7) mol/L for epicatechin, 2 x 10(-4) mol/L similar to 1 x 1 x 10(-5) mol/L for ascorbic acid. The detection limit (S/N = 3) is 6 x 10(-6) mol/L, 4 x 10(-7) mol/L and 1 x 10(-6) mol/L, respectively for these three analytes. This method has been successfully used for the determination of these analytes in tea samples and the assay result was satisfactory.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2001年第9期1072-1075,共4页
Chinese Journal of Analytical Chemistry
基金
中国科学院长春应用化学研究所电分析化学开放研究实验室资助课题
关键词
毛细管电泳
电化学检测
咖啡因
表儿茶素
抗坏血酸
茶叶
capillary zone electrophoresis
electrochemical detection
tea
caffein
epicatechin
ascorbic acid
