HPLC Determination of Tea Polyphenols and Caffeine in Green Tea

HPLC was applied to the determination of gallic acid (GA), caffeine (CAF) and 5 catechinic compounds, namely: catechin (C), epicatechin (EC), epigallocatechin gallate (EGCG),epicatechin gallate (ECG) and gallocatechin gallate (GCG), in green tea. Readjustment of composition of the mobile phase used in GB method of GB/T 8313-2008 was made by reducing the concentration of acetic acid from 2% to 0.5%. The 7 components were separated on AT. Lichrom ODS column (4.6 mm×250 mm, 5 μm). Flow rate of the mobile phase was set at 1.0 mL·min-1 and UV-detection at 278 nm was adopted in the determination. Seven components were completed separated within 40 min. Linear relationships between values of peak area and mass concentration of the 7 components were obtained in definite ranges. The proposed method was used in the analysis of green tea, giving values of recovery obtained by standard addition method in the range of 96.0%-102.8%.