超高效液相色谱-质谱联用分析茶叶中酚酸类化合物的组成及分布

采用超高效液相色谱-串联质谱技术建立同时测定茶叶样品中游离型、游离酯型、结合型、可溶性糖苷型及不溶性糖苷型等不同形态酚酸的分析方法。以70%甲醇溶液直接提取样品中的游离型酚酸，该提取液分别以2 mol/L NaOH溶液（含1 g/100 mL抗坏血酸和10 mmol/L乙二胺四乙酸）和1 mol/L HCl溶液水解以释放游离酯型与可溶性糖苷型酚酸；提取后的样品残渣分别以碱水解、酸水解方式释放结合型与不溶性糖苷型酚酸。23 种酚酸类化合物在50～1 000 μg/L范围内呈良好线性关系，相关系数（r）均高于0.996，相对标准偏差小于8.84%；茶叶样品中游离型酚酸的回收率为71.14%～105.43%，游离酯型酚酸和可溶性糖苷型酚酸的回收率分别为82.81%～108.93%、39.09%～102.25%。在茶叶中鉴定出14 种酚酸类化合物，总含量范围为7.84～12.90 mg/g。

Analysis of the Composition and Distribution of Phenolic Acid Compounds in Tea by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry

An analytical method for simultaneous determination of phenolic acid compounds (free phenolic acids, free phenolic acid esters, bound phenolic acids, soluble phenolic acid glycosides and insoluble phenolic acid glycosides) in tea samples was established by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The free phenolic acids in samples were extracted with 70% methanol, and the extract was hydrolyzed with 2 mol/L NaOH solution (containing 1 g/100 mL ascorbic acid and 10 mmol/L EDTA) and 1 mol/L HCl solution, separately, to release free phenolic acid esters and soluble phenolic acid glycosides, respectively. The reside after extraction was hydrolyzed by alkali and acid, separately, to release bound phenolic acid and insoluble phenolic acid glycosides. The calibration curves for the 23 phenolic acid compounds showed good linearity in the range of 50–1 000 μg/L, with correlation coefficients (r) higher than 0.996, and the relative standard deviation was less than 8.84%. The recoveries of free phenolic acids in tea samples were 71.14%–105.43%, and the recoveries of free phenolic acid esters and soluble phenolic acid glycosides were 82.81%–108.93% and 39.09%–102.25%, respectively. Fourteen phenolic acid compounds were identified in tea, with a total content ranging from 7.84 to 12.90 mg/g.