A fast and sensitive HPLC-DAD method for the determination of catechin and caffeine in black tea.
A gradient elution HPLC-DAD method has been developed for sensitive and fast determination of five main catechins,namely epigallocatechin gallate(EGCG),epigallocatechin(EGC),epicatechin gallate(ECG),epicatechin(EC),and catechin(+C),and caffeine in teas.The optimial wavelength was found at 205 nm,where limit of detections(LOD) for catechins and caffeine obtained were in the range of 0.01~0.04 μg·mL-1.Reverse-phase C18 column(150×4.6 mm ID,5 μm particle size;Agilent) and gradient elution consisted of acetonitrile and 0.03% trifluoroacetic acid solution(v/v) were employed for HPLC separation,in which,at 1 mL·min-1 of flow-rate,the extract was determined within 15 min.Recoveries were in range of 92%～110%,and repeatability expressed as RSD was less than 2.7%.Because of stability and specialty,the developed technique can be used as an ideal analytical method for determination of five catechins and caffeine in black tea.