亲水作用色谱-串联质谱法测定茶叶中γ-氨基丁酸和茶氨酸

Determination of γ-Aminobutyric Acid and Theanine in Tea by Hydrophilic Interaction Liquid Chromatography with Tandem Mass Spectrometry

粉碎后的茶叶样品用水在90℃水浴中提取10min(重复提取3次),提取液合并后,用水定容至50mL,移取1.00mL过0.22μm滤膜,采用亲水作用色谱-串联质谱法测定滤液中γ-氨基丁酸和茶氨酸的含量。以Waters Atlantis HILIC氨基色谱柱为固定相,以不同体积比的水和乙腈(9+1)溶液(含2mmol·L^(-1)乙酸铵和体积分数为0.1%的甲酸)的混合液为流动相进行梯度洗脱,串联质谱分析中采用电喷雾正离子模式和多反应监测模式。γ-氨基丁酸和茶氨酸的质量浓度均在5.00～500.00μg·L^(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)依次为1.00,0.50μg·L^(-1)。方法用于茶叶样品的分析,加标回收率为97.8%～107%,测定值的相对标准偏差(n=9)为4.9%～7.1%。

The pulverized tea sample was extracted three times for 10 min with water in 90 ℃ water bath.Volume of the combined extract was made up to 50 mL with water.1.00 mL of the above solution was filtered on0.22μm filtering membrane.Hydrophilic interaction liquid chromatography with tandem mass spectrometry was applied to the determination ofγ-aminobutyric acid and theanine in the filtrate.Waters Atlantis HILIC NH2 chromatographic column was used as stationary phase,and the mixture of water and acetonitrile(9+1)solution(containing 2 mmol·L-1 ammonium acetate and formic acid with 0.1% volume fraction)mixed in different ratios was used as mobile phase in gradient elution.ESI+and multi-reactions monitor mode were adopted in MS/MS.Linear relationships between values of peak area and mass concentration ofγ-aminobutyric acid and theanine were kept in the same range of 5.00-500.00μg·L-1,with detection limits(3 S/N)of 1.00,0.50μg·L-1,respectively.The proposed method was applied to the analysis of tea samples,giving values of recovery found by standard addition method and RSDs(n=9)of determined values in the ranges of 97.8%-107%and 4.9%-7.1%,respectively.