超高效液相色谱-串联质谱法测定茶叶中游离氨基酸成分

建立了使用超高效液相色谱-串联质谱(UHPLC-MS/MS)高效、快速直接测定茶叶中游离氨基酸的方法。通过对质谱、色谱条件及氨基酸提取条件的优化,以含0.2%(体积分数)甲酸的5 mmol/L 乙酸铵水溶液和甲醇为流动相进行梯度洗脱,在电喷雾离子(ESI)源正离子扫描模式下检测,通过 UHPLC -MS/MS测定,共解析了茶叶中的20种氨基酸。结果表明,茶氨酸(Thea)、Arg、Asn和Asp在50~500 μg/L 范围内线性关系良好,其他氨基酸在10~250 μg/L 范围内线性关系良好,相关系数均大于0.99;加标回收率为92.3%~109.2%,相对标准偏差为2.00%~9.88%,检出限为0.001~0.011 mg/L ,定量限为0.010~0.053 mg/L 。该方法灵敏、准确,具有良好的重复性和稳定性,可有效检测出茶叶中的20种氨基酸及氨基类成分。

Detection of free amino acids in tea using ultra-high performance liquid chromatography-tandem mass spectrometry

To efficiently and quickly detect free amino acid components in tea, a method using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. With the optimization of mass spectrometry, chromatographic conditions, and amino-acid extraction conditions, a total of 20 free amino acids were identified using 5 mmol/L ammonium acetate aqueous solution containing 0.2% (v/v) formic acid and methanol as mobile phases for gradient elution and detected by electrospray ionization (ESI) and positive-ion scanning. The results showed that all calibration curves expressed good linearities. Theanine (Thea), Arg, Asn, and Asp were in the range of 50-500 μg/L. The other amino acids were in the range of 10-250 μg/L with all correlation coefficients ≥ 0.99. The average recoveries were between 92.3% and 109.2%. The relative standard deviation (RSDs) were between 2.00% and 9.88%. The limits of detection (LODs) were 0.001-0.011 mg/L, and the limits of quantification (LOQs) were 0.010-0.053 mg/L. The method is sensitive, accurate, and has good repeatability and stability. The method can effectively detect 20 types of amino acids and amino components in tea leaves from the samples of green tea, white tea, and black tea.