测定饮料中咖啡因含量的综合性实验.

This experiment for determination of caffeine content was designed in the paper. Firstly, using solvent extract method, caffeine crystal was extracted from tea by ethanol as a solvent. Then the effect of mobile phase in sample separation has been investigated by HPLC. As increasing the concentration of methanol, the retention time of caffeine decreased accordingly. Next, the external standard method was established to detect the caffeine concentrations in high-performance liquid chromatography. The linear equation A = 2.38 C + 33.4 held a good linear fitting in the range of 20-100 μg / mL. and the square of the correlation coefficient was 0.991. Finally, caffeine concentrations in several beverages such as green tea, coke and energy drinks bought from supermarket were detected by HPLC, No interference peaks were observed in the chromatograms. Caffeine was found in all of these beverages, so the public should reduce intake of caffeine containing drinks. [ABSTRACT FROM AUTHOR]