Short Semester Research Project
Determination of polyphenol content in a variety of tea
Tea polyphenol is a series of polyhydroxy phenolic compounds in tea trees, and the mass fraction is the highest in tea ( 30%), especially green tea. For the determination of polyphenols, we got potassium permanganate titration method, iron tartrate colorimetry (UV-Vis spectrophotometry), atomic absorption spectrophotometry, gas chromatography, high performance liquid chromatography, capillary electrophoresis determination and so on from the former studies. In this experiment, we used iron tartrate colorimetry (UV-Vis spectrophotometry).
Polyphenols and tartaric acid iron can generate a purple-brown complexion, and the depth of color is proportional to the amount of polyphenol contents. In this experiment, the calibration curve was made with gallic acid ethyl ester, and the depth of color was determined with UV-Vis spectrophotometer. Based on the calibration curve, and then multiplied by the conversion coefficient, we can get the amount of the tea polyphenols in different samples.
Three kinds of Chinese tea samples was tested in this experiment: Green tea (36.0%), Iron Goddess of Mercy (29.4%) and Hong Qi (22.4%). It's obvious that the amount of the tea polyphenols is the highest in green tea, which also goes with other studies.
- This is a basic experiment in analytical chemistry, and I conducted this experiment when I was a Freshman. Although easy experiment, I think it helps me to lay good foundation in experiment operation and also has great influence in my later study.
- East China University of Science and Technology, Department of Chemistry, 04/2009
- Advisor: Dr. Xin Yin
