Determination of the concentration of caffeine, theobromine, and gallic acid in commercial tea samples

Green tea, one of the most widely consumed beverage in the world, has many health benefits due to compounds such as caffeine, theobromine, and gallic acid. Highperformance-liquid chromatography was used to determine the concentration of caffeine in commercial green tea samples. Introduction Green tea is the most commonly consumed beverage in the world after water.1 It is derived from the tea plant Camellia sinensis. The extent of fermentation of the tea plant determines the type of tea. Oolong and paochong teas are partially fermented; black and red teas are fully fermented; and green teas are nonfermented.2 The nonfermented green tea supposedly contains the highest concentration of polyphenols.3 Polyphenols are powerful antioxidants which are compounds that may protect cells from damage by breaking down free radicals. Green tea has many different compounds, including proteins, carbohydrates, xanthic bases, pigments, volatile compounds, minerals and trace elements, and polyphenols and phenolic acids.1 Some important compounds, such as those analyzed by Fernandez et al. include caffeine, theobromine, and catechins such as gallic acid. Caffeine and theobromine are alkaloids that share a similar structure. The compounds also have similar effects as nervous system stimulants and diuretics. Gallic acid is a phenolic acid and an antioxidant. The structures of these three compounds are shown in Figure 1. Figure 1. Structures of Caffeine, theobromine, and gallic acid Green tea is growing in popularity in the United States because of its health benefits. It has been used as a medicine since ancient times. Chinese medicine has used it as treatment for headaches, body aches and pains, digestion, depression, and an energizer.1 Green tea is also thought to have antimutagenic and anticarcinogenic potential, due to the large number of antioxidants. For that reason, the health benefits of green tea have been researched. It is important to determine the concentrations of such helpful compounds in Concordia College Journal of Analytical Chemistry 2 (2011), 31-35 32 different tea samples. College students in particular are consuming more and more tea as its availability increases. Green tea is available in supermarkets, either in bag form or bottled, or in cafes and coffee shops. The composition of these teas may or may not be similar. It is important to know the relative concentrations of beneficial compounds such as caffeine, gallic acid, and theobromine. In a method based off of Fernandez et al.2, caffeine, theobromine, and gallic acid concentrations were attempted to be determined using HPLC analysis.