超高效液相串联质谱检测茶叶及茶饮料中咖啡因含量

建立超高效液相串联质谱检测茶叶及茶饮料中咖啡因含量的方法。茶叶及茶饮料经前处理后进样,以0.1%甲酸水溶液-乙腈(80:20,v/v)为流动相等度洗脱,流速为0.3 mL/min,经C₁₈色谱柱分离,柱温25 ℃;质谱采用电喷雾离子源正离子模式、多反应检测模式检测,脱溶剂气(N₂)温度500 ℃、流速700 L/Hr,毛细管电压3.5 kV,锥孔电压55 V,碰撞气为高纯氩气。在上述分析条件下,本法咖啡因的检出限为2.0 μg/L;在2.0~1000 μg/L浓度范围内的线性关系良好,相关系数r为0.9969;加标回收率达90.2%~103.9%;相对标准偏差在1.00%~3.00%(n=6)。本方法简便、快速,选择性、重现性好、灵敏度高,适用于茶叶及茶饮料中咖啡因的定量分析,结果准确可靠,对于复杂样品中咖啡因的检测有明显优势。

Examination of Caffeine in Tea and Tea Drinks by Ultra-lipid Chromatography-tandem Mass Spectrometry

A new method,ultra-lipid chromatography-tandem mass spectrometry,which was used to exam the caffeine in tea and tea drinks,was developed in this experiment. After tea and tea drinks being pretreated,samples were separated by C18 column and the column temperature was 25 ℃ with 0.1% formic acid solution-acetonitrile( 80∶ 20,v/v) as the mobile phase for gradient elution,and the flow rate was set at 0.3 mL/min.The electrospray ionization source of MS in positive ion mode was used for multiple reaction monitoring,under conditions included that desolvation gas( N2) temperature was 500 ℃ and the flow rate was 700 L/Hr,capillary voltage was 3.5 kV,cone voltage was 55 V and collision gas was high purity argon. Under conditions above,the limit of detection( LOD) of caffeine was 2.0 μg/L. There was a perfect linear relationship in relative concentration range( 2.0~1000 μg/L),and the correlation( r) was 0.9969,average recoveries were in the range from 90.2% to103.9%,and relative standard deviations( RSDs) were among 1.00% to 3.00%( n = 6).The established method was convenient,fast and had good selectivity,good reproducibility and high sensitivity. It was suitable for quantifying caffeine in tea and tea drinks,the method was accurate and reliable,and had an advantage in detecting caffeine contained in complex samples.