Determination of theobromine and caffeine in some Malaysian beverages by liquid chromatography-time-offlight mass spectrometry

Purpose: To determine the concentration of theobromine (TB) and caffeine (CF) in tea and other beverages using liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS). Methods: The extract of caffeine and theobromine from tea and other beverages was filtered by 0.45 μm nylon micro-syringe and then injected into a LC-ToF-MS system. Theobromine and caffeine were separated using Thermo Scientific C18-column (length 250 mm, width 2.1 mm and diameter 5 μm). Acetonitrile-methanol (ACN – MeOH, 3:1 v/v) was used as mobile phase B, while mobile phase A was 0.1 % FA in DIW. The volume injected was 30 μL at a rate of 0.3 mL/min. Results: Good linearity was obtained in the range of 0.3 – 400 and 0.2 – 200 mg/L for theobromine and caffeine, respectively (regression coefficient (R2) > 0.970). The limits of detection were 0.15 and 0.05 μg/mL for theobromine and caffeine,  respectively. The highest concentrations of caffeine and theobromine determined in tea samples were 159.1 and 255.8 mg/L, respectively. Conclusion: Theobromine and caffeine have been successfully analysed in tea, coffee and soft drinks. LC-TOF-MS is an accurate and promising instrument for the  determination of the studied compounds in beverages. Keywords: Theobromine, Caffeine, Tea, Coffee, LC-TOF/MS