Determination and Characterization of Caffeine in Tea, Coffee and Soft Drinks by Solid Phase Extraction and High Performance Liquid Chromatography (SPE - HPLC)

Caffeine (1,3,5-trimethylxanthine), a mild addicting drug was isolated, purified and characterized from tea (black and green) and coffee. Isolation was done by liquid-liquid extraction using chloroform as an extracting solvent. Extraction was carried out in four steps such as leaching, dye removal, liquid extraction and recrystallization. Crude caffeine was purified by solid phase extraction (SPE) method. The solvent used for recrystallization were toluene and petroleum ether. The purity of caffeine was ascertained by the determination of melting temperature. Pure caffeine obtained from different samples was characterized by UV-Visible spectrophotometer, TLC, FT-IR and HPLC. In HPLC, 50mM KH2PO4 (pH=2), acetonitrile and methanol (40:8:2) was used as solvent as well as mobile phase. Amount of caffeine in various soft drinks (Cola) commercially available in Bangladesh was also determined by HPLC method.