Full Validation of a Simple Method for Determination of Catechins and Caffeine in Brazilian Green Tea ( Camellia sinensis var. assamica) Using HPLC.

This paper describes the validation of an HPLC method for the assay of a green tea brew. The method employs a RP-18 column with water:methanol:ethyl acetate elution and UV detection at 280 nm. Specificity was evaluated using a photodiode array detector. The validation data showed that the assay is specific, accurate, precise, and reproducible for determination of six catechins and caffeine simultaneously. The response was linear over a range of 37–185 μg mL⁻¹ for caffeine, 99–500 μg mL⁻¹ for (−)-epigallocatechin (EGC), 20–100 μg mL⁻¹ for (+)-catechin (C), 30–150 μg mL⁻¹ for (−)-epicatechin (EC), 150–800 μg mL⁻¹ for (−)-epigallocatechin gallate (EGCG), 20–105 μg mL⁻¹ for (−)-gallocatechin gallate (GCG) and 40–205 μg mL⁻¹ for (−)-epicatechin gallate (ECG) ( r > 0.9999 for all compounds). The range of recoveries was 96.12–110.48% according to substances. The RSD values for intra- and inter-day precision studies were <2.07 and <6.65%, respectively. The composition of samples assayed suggests that the summer is the best season for extract a major content of EGCG and caffeine. This assay can be readily utilized as quality controlled method for major green tea compounds. [ABSTRACT FROM AUTHOR]