| Abstract
| - We developed a high-performance liquid chromatography-based method for simultaneous analysisof nine catechins, gallic acid, strictinin, caffeine, and theobromine in green tea by using catechol asan internal standard. Although the high cost and instability of the catechin reference standards limitthe application of this method, the addition of ascorbic acid to the standard stock solution preservedthe stability of the reference standards in the solution for 1 year when stored at −30 °C. Furthermore,we found that the slopes of the calibration curves plotted were stable for a run time of 2000 h. Ourmethod proved to be appropriate for quantification and yielded good correlation coefficients, detectionlevels, repeatability, reproducibility, and recovery rates. Quantitative data revealed that the contributionof only 200 mL of brewed tea to the total dietary catechins was approximately 220−420 mg, whilethat of 500 mL of bottled tea was approximately 170−900 mg. Keywords: Green tea; catechins; gallic acid; strictinin; alkaloid; HPLC
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