[Determination of theaflavins in black tea by high performance liquid chromatography]

A high performance liquid chromatographic method for the determination of theaflavins has been established. Separation was carried out on an ODS column (Shim-pack VP-ODS column, 4.6 mm i.d. x 150 mm) at 40 degrees C with a linear gradient elution of acetonitrile-ethyl acetate (21:3, v/v) and aqueous acetic acid (2%), and UV detection at 280 nm. The experimental results showed a good linear relationship between the peak area and the concentration of theaflavins (r = 0.9990-0.9992). The average recoveries (n = 5) for theaflavin products were 96.88%-103.57%. The average relative standard deviation was less than 1.5%. The results show that the method is simple, rapid and accurate for the determination of theaflavins in black tea and theaflavin extract.