A HPLC Method for Detection of 17 Characteristic Components in Tea Extract

A HPLC method has been developed for the determination of tea for seven catechins ((+)-catechin, (−)-epicatechin, (−)-epigallocatechin, (−)-epigallocatechin gallate, (−)-epicatechin gallate, (−)-gallocatechins and (−)-gallocatechin gallate), two flavonols (quercetin, kaempferol), seven organic acids (Gallic acid, ferulic acid, protocatechuic acid, p-hydroxybenzoic acid，p-coumaric acid, erucic acid，vanillic acid) and caffeine. Using HPLC with gradient elution and photodiode array detection, seventeen compounds were separated and detected by optimizing the column temperature, mobile phase ratio and detection wavelength. The validity of this method was confirmed by the quantitative measurement of seventeen characteristic compounds. The correlation coefficient of all standards curve was 0.9967~1.0000 and the detection limits (s/N = 3) were 0.010~1.2 mg/L. The average recoveries of 17 characteristic components were between 81.50 and 124.80%. 59 green tea samples (origin: Hangzhou, China) were analyzed and 11 characteristic components were found in all samples and their content of different samples varied greatly. The catechins were the most abundant constituents in teas with up to 79.5~156.6 g/kg and the contents of (−)-epigallocatechin gallate were the highest. Quercetin and kaempferol were only found in some tea samples. Protocatechuic acid, p-hydroxybenzoic acid, ferulic acid and erucic acid were not detected in the tea samples. This method is ideally suited for routine analysis for the determination of bioactive components in green tea with good repeatability and accuracy of results. Furthermore, this method can be applied to all kinds of tea and tea products and provided a detection method for establishing the HPLC fingerprint of a certain tea.