摘要
目前对茶叶中的5种儿茶素进行分离测定一般采用GB/T 8313—2008《茶叶中茶多酚和儿茶素类含量的检测方法》中的方法,但在实际测定过程中,发现测定结果的重复性较差,空白、标准溶液与样品的溶剂不一致,标准溶液配制过程中标准品不能完全溶解,对国标中儿茶素的测定方法进行改进,用10 m L预热过的体积分数70%甲醇溶液在70℃条件下重复提取3次,合并提取液,用水定容。利用高效液相色谱仪在波长278 nm处进行检测。流动相A为体积分数0.1%乙酸溶液,流动相B为乙腈,洗脱程序为A的初始比例为95%,5 min内A的比例降至90%,保持至15 min,15-20 min内A的比例降至80%,20-25 min内A的比例升至90%,25-30 min内A的比例恢复至95%。结果表明：采用本方法测定茶叶中5种儿茶素含量可以保证标准溶液与样品溶剂的一致性,提取较完全,减少了因操作带来的误差,重复性较好,其相对标准偏差为0.75%-4.50%,分离度为0.58-4.35,方法的回收率为81.4%-113.0%,其相对标准偏差均在1.21%-7.71%之间。
At present, the five catechins in tea are commonly separated and determined according to the Chinese National Standard GB/T 8313—2008, but the results of actual measurement show that the repeatability of this method is poor. Moreover, different solvents are used in blank, standard and sample solutions, and standard substance is not be completely dissolved in the solvent. In this study, an attempt was made to improve these drawbacks. Tea samples are extracted three times at 70 ℃ with 10 m L of 70% preheated methanol solution, and then the extracts were combined and brought up to the final volume with water. The analytes were determined using high performance liquid chromatograph（HPLC） with UV detection at 278 nm. Mobile phase A was 1% acetic acid solution while mobile phase B was acetonitrile. The gradient elution program used was as follows： 0–5 min, 95%–90% A; 5–15 min, 90% A; 15–20 min 90%–80% A; 20–25 min, 80%–90%A; and 25–30 min, 90%–95% A. The results showed that the developed extraction technique that ensured that the solvents of standard solution and samples were consistent allowed complete extraction of catechins, reducing errors arising from the manual handling and having good repeatability. The relative standard deviations（RSDs） for 5 replicate determinations were in the range of 0.75%–4.50%, and the degrees of separation were 0.58–4.35. Recoveries of spiked sample ranged from 81.4% to 113.0%, with RSDs between 1.21% and 7.71%.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2016年第6期137-141,共5页
Food Science
基金
国家质检总局科技计划项目(2014IK119)
关键词
茶叶
儿茶素
测定方法
改进
tea
catechin
determination method
improvement
