摘要
用分光光度法研究了咖啡因作为电子给予体与电子接受体四氯对苯醌的荷移反应。确定了反应及测定的条件为:在硼砂与NaOH构成的缓冲溶液中,咖啡因分别与四氯对苯醌混匀于(20±1)℃的水浴中恒温20 min,可形成1:2的稳定荷移络合物,其可见光区内的最大吸收波长为λ_(max)=536 nm,表观摩尔吸光系数ε= 1.684×10~4L/mol·cm,最低检测限为1.9μg/mL,在1×10^(-5)～3.0×10^(-4)mol/L内符合比耳定律,线性方程为△A=1.485 6×10~4-0.0406(r=0.997)。该法对市售的茶叶和茶饮料中咖啡因含量测定的结果与GB/T 16344—1996法一致,回收率在99.1%～102.8%,RSD为2.0%～3.3%,茶叶经热水漫泡处理和茶饮料的直接测定与CHCl_3萃取处理的效果一样,茶叶和茶饮料中共存的其他组分不干扰测定。
The charge transfer reaction of caffeine with tetrachlorobenquinone in borax buffer forms a 1： 2 complex with the apparent molar absorptivity of 1. 684× 10 ^4 L/（mol · cm） and the minimum detectability of 1.9 μg/mL at 536nm. Beer＇s law is obeyed in the range of 1× 10^-5 -3.0 × 10 ^-4 mol/L with the relative standard deviation of 2.0%-3.3% and the recovery of 99.1%-102.8%. This method was successfully applied to the determination of caffeine content in tea and its beverage. The other components contained in tea and its beverage did not interfere in the assay. The results showed that this method is simple, rapid and accurate, the resuhs were satisfactory.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2008年第3期177-181,共5页
Food and Fermentation Industries
关键词
荷移反应
分光光度法
咖啡因
茶叶和茶饮料
四氯对苯醌
charge transfer reaction, spectrophotometry, caffeine, tea and tea beverage, tetrachlorobenquinone
作者简介
硕士，教授。
