Simultaneous determination of catechins and alkaloids in brick-tea by high performance liquid chromatography-diode array detection.

Objective To develop a method for determination of catechins and alkaloids in brick-tea by high performance liquid chromatography(HPLC) with diode array detection(DAD),and to explore optimum extraction conditions for catechins and alkaloids components in brick-tea.Methods Catechins and alkaloids were separated and detected by HPLC.Orthogonal experiment and paired t test was carried out to compare the effect of water and alcohol as extraction solvents and to obtain optimum extraction conditions for extracting catechins and alkaloids components in brick-tea.Results Six kinds of catechins of catechin,epicatechin,gallocatechin,epigallocatechin,epicatechin gallate,epigallocatechin gallate and two kinds of alkaloids of caffeine and theobromine were separated and detected simultaneously.Calibration curves between peak areas and concentration of each component in bricktea were linear within a suitable concentration range,and coefficients of determination (R2) were between 0.9990-0.9999; spiked recoveries were from 83.78％ to 106.35％,and relative standard deviations(RSD) were between 0.50％-1.51％.The optimum extraction condition for catechins and alkaloids was 80％ ethanol,solid-liquid ratio of 1:10,temperature 80 ℃ and extraction time 30 min.Conclusion Alcohol as extraction solvents with optimal combination on HPLC,six kinds of catechins and two kinds of alkaloids are separated accurately,qualitatively,rapidly and sensitively. Key words: Chromatography, high pressure liquid;  Catechin;  Alkaloids ;  Orthogonal test