Abstract
Abstract Methylxanthines such as caffeine, theophylline, theobromine are significant and widespread psychoactive substances. We developed the isocratic method with optimum composition of the mobile phase 90 % water: 10 % acetonitrile and confirmed repeatability of retention times and peak areas. The developed HPLC method was applied to determine the content of methylxanthines in selected types of black and green teas available on the market. Of the black teas (tea bags), the highest concentration of theobromine was found in Ceylon tea (18.98 mg.L−1). The highest concentration of caffeine was in a cup of Earl Gray tea (254.09 mg.L−1). Among loose black teas, the highest content of both theobromine and caffeine was found in Pu Erh Superior tea, where the theobromine content was 24.62 mg.L−1 and the caffeine content was 520.67 mg.L−1. Of green powder teas, highest caffeine content (306.46 mg.L−1) was in Shizuoka Matcha Premium and the highest content of theobromine (8.45 mg.L−1) was found in GABA Midori. From the loose green tea, the highest concentration of theobromine (12.85 mg.L−1) was in Lung Ching West Lake. The highest caffeine content (484.85 mg.L−1) was in Gyokuro Shizuoka Premium Tea. In both types of teas the amount of theobromine and caffeine was quantified, but the presence of theophylline was not proven. Data on contents of these metabolites in tea products are highly informative for consumers.
Highlights
Several mild psychostimulants are derived from methylxanthines, including widely used and highly popular caffeine, theobromine and theophylline (Xia et al 2013)
The methylxanthines studied are structurally very similar, it was necessary to choose the proper composition of the mobile phase for their separation
Prepared tea extracts were analysed by developed highperformance liquid chromatography (HPLC) method and the peaks of the methylxanthines were subsequently identified by comparison of UV spectra and retention times with corresponding data of the standards
Summary
Several mild psychostimulants are derived from methylxanthines, including widely used and highly popular caffeine, theobromine and theophylline (Xia et al 2013). Weights of both green and black tea samples, leaching time and water temperature were different depending on tea as shown in the Table 2. We determined the content of caffeine and theobromine in tea samples, we did not perform the method repeatability for theophylline.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
