ABSTRACT
OBJECTIVE: To develop an HPLC method for simultaneous determination five eatechins, including (+)-catechin, epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin-3-gallate, as well as caffeine in Oolong tea. METHODS: The HPLC analysis was carried out on a Grace Allitima C18 column (4.6 mm × 250 mm, 5 μm), with a gradient elution acetonitrile-0.2% acetic acid at the flow rate 1.0 mL · min-1. The detective wave length was set at 280 nm, and the column temperature was set at 35℃. RESULTS: The calibration curve was linear within the range 5.95-952 μg · mL-1 for catechin, 6.36-1018 μg · mL-1 for epicatechin, 6.55-1048 μg · mL-1 for epigallocatechin, 7.80-1248) μg · mL-1 for epigallocatechin gallate, 10.83-1732 μg · mL-1 for epigallocatechin-3-gallate, and 13.38-2 140 μg · mL-1 for caffeine, respectively. The average recoveries for six determined marker compounds were 99.12%-102.12%. CONCLUSION: This method is simple, accurate, and practical for quality control Oolong tea. There are some differences in the contents the six marker compounds in the samples from different producing areas and different collection periods.