液相色谱-串联质谱法同时测定饮料中的咖啡因、茶碱和可可碱

Simultaneous determination of caffeine,theophylline and theobromine in drinks by liquid chromatography-mass spectrometry

目的建立市售饮料中咖啡因、茶碱和可可碱的液相色谱-串联质谱法(LC-MS/MS)。方法将饮料用水稀释100倍后,采用三氯甲烷∶异丙醇(9∶1,V/V)进行提取,提取液经Allure PFP Propyl柱(100 mm×2.1 mm,5μm)分离,以5 mmol/L乙酸铵溶液(含5%甲醇、0.05%的甲酸)-甲醇为流动相进行梯度洗脱,采用电喷雾正离子化(ESI+)、多反应监测模式同时测定咖啡因、茶碱和可可碱。结果咖啡因、茶碱和可可碱在10 ng/ml^1000 ng/ml范围内方法的线性相关系数(r)均>0.9970,检出限为2 ng/ml^5 ng/ml,加标回收率均>60.68%,精密度均<14.41%。应用于实际市售饮料中,均检出咖啡因成分,部分饮品检出茶碱、可可碱成分。结论该方法简便、灵敏,可用于监测市售饮料中咖啡因、茶碱、可可碱的含量。

Objective To establish a rapid determination method with liquid chromatography-tandem mass spectrometry(LC-MS/MS)for caffeine,theophylline and theobromine in drinks.Methods After one hundred times dilution,the target analytes in drinks were extracted with chloroform-isopropanol(9∶1,V/V),and then separated on an Allure PFP Propyl column(100 mm×2.1 mm,5μm)with a mobile phase of methanol-5 mmol/L ammonium acetate(containing 5%methanol and 0.05%formic acid)using gradient elution.For mass spectrometric detection,electrospray ionization(ESI+)in positive mode and multiple reaction monitoring(MRM)were used.Results The linear correlation coefficient(r)of the method was greater than 0.9970 when the concentrations of caffeine,theophylline and theobromine were within 10 ng/ml-1000 ng/ml,with the detection limits of 2 ng/ml-5 ng/ml.The spiked recovery was more than 60.68%,and the precision was less than14.41%.When it was applied to actual commercial beverages,caffeine was detected in all beverages,and theophylline and theobromine were detected in some beverages.Conclusion This method is simple and sensitive,and it can be applied to monitor the concentrations of caffeine,theophylline and theobromine in drinks.