An improved HPLC method for simultaneous determination of phenolic compounds, purine alkaloids and theanine in Camellia species

A simple and fast HPLC analysis method for phenolic compounds, purine alkaloids and theanine in various Camellia species was developed. Using an amide-C16 column, catechins, gallic acid, caffeine, theobromine, theacrine, theophyline and theanine could be rapidly separated within 45 min with a gradient elution system. Excellent linearity was observed for all 14 compounds in the range studied, with correlation coefficients between 0.9994 and 0.9999. Limit of detection and limit of quantification of the 14 compounds varied from 0.0001 to 0.072 ng/μL and 0.0004 to 0.24 ng/μL, respectively. Four kinds of Camellia species were analyzed using this method. In traditional cultivated tea trees, Camellia sinensis and Camellia assamica, the main purine alkaloid was caffeine and main phenolic compound was (−)-epigallocatechin gallate (EGCG). The main purine alkaloids in Camellia ptilophylla and C. assamica var. kucha were theobromine and theacrine; their contents were 4.001±0.1184% dry weight and 2.116±0.0270% dry weight, respectively. The main phenolic compounds in C. ptilophylla and C. assamica var. kucha were (−)-gallocatechin gallate (GCG) and EGCG respectively. The content of theanine in the four Camellia species samples ranged from 0.136±0.0026% to 1.485±0.0491% dry weight.