Abstract: A capillary zone eletrophoresis method was proposed for the content determination of caffein, theanine, (-)-epicatechin and (-)-epigallocatechin gallate in tea. The electrolyte solution consisted of 20 mmol/L borax-phosphate (pH 9.5). The voltage and column temperature were 25 kV and 25 ℃, respectively. The detection wavelength was set as 210 nm. Complete separation of the four analytes was achieved within 8 min. A good linear relationship between absorbance and concentration was observed for each analyte with a correlation coefficient varying from 0.9944 to 0.9995. The limits of detection of this method were 0.001–0.01 μg/mL. Average spike recoveries of affein, theanine, (-)-epicatechin and (-)-epigallocatechin gallate in different kinds of tea varied from 89.98% to 102.7%, with RSDs less than 9.11%. This method has been successfully used for the determination of these compounds in tea samples.

Key words: capillary zone electrophoresis, tea, caffeine, theanine, (-)-epicatechin and (-)-epigallocatechin gallate