Abstract: A rapid method for simultaneous determination of the contents of theobromine, theophylline and caffeine in beverages by high performance liquid chromatography (HPLC) with a titania-based reverse-phase column was developed. The proposed method presented good linearity (R2 > 0.999 0) for theobromine, theophylline and caffeine in the range of 5–500, 5–1 000 and 6–1 200 mg/mL, respectively, under the optimum?conditions, and the limits of detection (LODs) for them were 0.04, 0.08 and 0.03 mg/mL, respectively. The recoveries of spiked samples were 99.0%–102.0%, 96.7%–106.7% and 99.4%–102.3%, respectively. The relative standard deviations (RSDs) of the precision for 9 replicate detections were less than 0.23%. This method was simple in operation and fast in analysis. Both the precision and accuracy could meet the requirements of quantitative analysis.?The method could be used for simultaneous determination of theobromine, theophylline and theobromine in food, giving satisfactory results. In addition, the thermodynamic parameters, entropy, enthalpy and Gibbs free energy, were calculated for the retention of the analytes. The retention behaviors of the three alkaloids were driven by enthalpy change ΔH0, and the retention sequence of theobromine, theophylline and theobromine was consistent with the experimental results.

Key words: titania-based reverse phase column, high performance liquid chromatography, thermodynamics, theobromine, theophylline, caffeine