EVALUATION OF A CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF PHENOLIC ACIDS AND METHYLXANTHINS IN TEA

Teas are play a very important role in the control of diseases mainly due to the presence of polyphenols and alkaloids present, associated with beneficial effects in relation to the central nervous system, anti-inflammatory and antioxidant action. 1 This study deals with the development of a separation and quantification method by high performance liquid chromatography with a diode array detector (HPLC- DAD), for the determination of six phenolic acids (gallic, trans-cinnamic, caffeic, ferulic and p-coumaric acids) and two methylxanthines (caffeine, theobromine) in tea (Camellia Sinensis) samples. Widely used in the evaluation of chromatographic separation, univariate optimization consists in the study of each variable (gradient, temperature and flow) in isolation. A univariate study was used for the optimization of factors affecting the chromatographic separation: gradient, flow and temperature of the oven. Changes in gradient conditions were evaluated using the parameters: retention time (Rt), retention factor (K), separation factor (α), resolution (Rs), and number of theoretical plates (N).2 The method was validated in terms of linearity, limits of detection and quantification, precision (repeatability and intermediate precision), accuracy (recovery), matrix effects and process efficiency. The Chromatographic separation optimized, showing good resolution, selectivity and sensitivity in the simultaneous determination of 8 compounds studied and the detection by DAD was adequate, showing low limits of detection