可可碱、茶碱和咖啡碱的快速测定及其色谱保留行为

Rapid Determination of Theobromine, Theophylline, and Theobromine and Their Chromatographic Retention Behaviors

建立基于钛胶反相色谱固定相快速测定食品中可可碱、茶碱和咖啡碱的高效液相色谱(high performance liquid chromatography,HPLC)法.结果表明,可可碱、茶碱和咖啡碱的标准曲线线性良好(R2>0.9990),线性范围分别为5~500、5~1000μg/mL和6~1200μg/mL,检出限分别为0.04、0.08μg/mL和0.03μg/mL,样品加标回收率分别为99.0%~102.0%、96.7%~106.7%和99.4%~102.3%,相对标准偏差(n=9)小于0.23%.3种生物碱在HPLC上的保留行为由焓变ΔH0驱动,保留顺序与实验结果相符,依次为可可碱、茶碱和咖啡碱.建立方法操作简单、分析速度快,精密度和准确度均可满足测定要求.用于食品中可可碱、茶碱和咖啡碱的同时测定,结果满意.

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 μg/mL, respectively, under the optimum conditions, and the limits of detection (LODs) for them were 0.04, 0.08 and 0.03 μg/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.