[Simultaneous analysis of theaflavins and catechins by capillary electrophoresis]

In order to monitor the changes of theaflavins and catechins during the process of tea polyphenol oxidation, a rapid, accurate, sensitive and convenient analytical method was established. The optimum analytical conditions for simultaneous analysis of four theaflavins (TFs) and six catechins by capillary electrophoresis were investigated. The electrolyte solution consisted of 200 mmol/L boric acid (pH 7.7), 10 mmol/L potassium dihydrogenphosphate, 9 mmol/L beta-cyclodextrin and 27.5% acetonitrile. The experimental conditions of the instrument were selected as follows: voltage 25 kV, column temperature 30 degrees C, and detection wavelength 200 nm. Ten constituents could be separated from each other completely within 8 min and each one had a good linear relationship between its peak area and corresponding concentration (nu = 0.990 7 - 0.999 8). Furthermore, their detection limits were from 0.39 to 0.88 microg/mL, the mean recoveries varied from 91.5% to 113.5%. The relative standard deviations were less than 5%. All the above results showed that the developed method is especially suitable for the analysis of theaflavins and catechins.