Simultaneous Extraction, Purification, and Quantification of Polyphenols, Caffeine, and Theophylline from BB35 Green Tea Leaves (Kenya cultivar) Using High-Performance Liquid Chromatography (HPLC) with Gradient Quantification

This study introduces a novel technique that uses a solvent mixture of 60% water and 40% ethanol to extract caffeine, theophylline, and polyphenols from green tea leaves (Camellia sinensis) all at once. On a dry basis, the Folin-Ciocalteu Reagent Method (ISO 14502-1) estimated the total polyphenol content of green tea leaves to be 25% (Gallic Acid Equivalent (GAE) in mg/g of dry sample). The extraction procedure showed remarkable effectiveness, recovering 94% of the caffeine, 92% of the theophylline, and 95% of the polyphenols. We verified each compound's stability and retention periods using HPLC-UV/PDA analysis at a fixed wavelength of 280 nm. The concentrations of the following compounds were noted: epicatechin at 19.2 ppm (RT 8.0 min), theophylline at 19.5 ppm (RT 3.2 min), catechin at 20.0 ppm (RT 7.2 min), and caffeine at 18.9 ppm (RT 4.0 min). These findings demonstrate the method's environmental advantages and scalability, suggesting that the nutraceutical industry may find use for it.