Simultaneous Determination of 12 Effective Ingredients in Green Tea Soup by Ultra-High Performance Liquid Chromatography

A method for simultaneous determination of 12 effective ingredients, including gallic catechin gallic acid ester, gallnut catechin gallic acid ester, epicatechin gallic acid ester, gallic acid, catechins gallic acid ester, epicatechin, table gallic catechin, catechin, gallic catechin, theanine, caffeine and theobromine in green tea soup by ultra-high performance liquid chromatography (UHPLC) was established. Tea powder sample of 1.00 g was dissolved with 100 mL of 90 ℃ water and extracted by ultrasound in 90 ℃ water bath for 20 min, then water was used to make its volume up to 100 mL. The above sample solution of 1 mL was taken and made its volume up to 10 mL with water. After centrifuge, the supematant was filtered by 0.22 μm filter membrane. Waters ACQUITY UPLC BEH C₁₈ column was used as stationary phase and a mixture of 0.01% (φ) phosphoric acid solution and acetonitrile with different volume ratios were used as mobile phase for gradient elution. The sample was detected by diode array detector at detection wavelength of 210 nm. The results showed that 12 effective ingredients could be separated within 16 min. Linear relationships between mass concentrations of 12 effective ingredients and their peak areas were kept in the definite range, with detection limits (3S/N) in the range of 3.2-15.6 mg·kg^-1. RSDs (n=6) of retention times and peak areas were found in the ranges of 0.13%-0.23% and 0.56%-3.9%, respectively. Recovery test was made on actual samples by standard addition method, giving results in the range of 89.2%-113%.