Simple isocratic method for simultaneous determination of caffeine and catechins in tea products by HPLC

Tea is a popular beverage almost all over the world. Many studies show that tea consumption is closely associated with positive health impact. Most of the HPLC methods used for the determination of tea constituents include gradient elution systems which involve expensive instrumentation. The objective of this study was to develop a simple, rapid precise and low cost HPLC method for the separation and quantification of catechins and caffeine in tea (Camellia sinensis). The method utilizes a phenyl column (2.1 × 150 mm) with a UV-detector (280 nm) where excellent chromatographic separation of tea components i.e. gallic acid (GA), caffeine (Caf), epicatechin (EC) and (-)-epigallocatechin gallate (EGCG) was achieved. The isocratic elution system of acetonitrile, glacial acetic acid and deionized water (8:1:91 v/v/v) at a flow rate of 0.5 mL/min was involved. This method produced excellent accuracy and precision. Within run and between run precision was less than 7.5 %. The equations for calibration curves were y = 0.117 (±0.010)x + 0.173 (±0.024), y = 0.100 (±0.003)x + 0.045 (±0.019), y = 0.016 (±0.001)x + 0.006 (±0.004), y = 0.025 (±0.001)x-0.025 (±0.007) for GA, Caf, EC and EGCG respectively. The method validation parameters prove that the method is efficient, a simple and adequate for the quantitative determination of principal components in tea samples.