关键词: 茶叶, 化学成分, 甘油, 提取, 质谱法, 定量

Abstract: In the present work, glycerin was used as alternative solvent to the traditional solvents such as methanol to extract different classes of chemical constituents from tea and its by-products. After extraction, ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-QQQ-MS/MS) was used to quantify seven classes of chemical constituents in tea. The extraction parameters were studied and optimized by single factor experiments, and the best extraction efficiency can be obtained under the following conditions: glycerin water content 50%, solid-liquid ratio 1:10, extraction time 10 min, extraction temperature 40 °C. By Optimizing the conditions of UPLC-QQQ-MS/MS, a quantitation method was established to measuring the contents of 130 substances which included catechins, phenolic acids, flavonoids, organic acids, amino acids, alkaloids and nucleotides. The results of method validation showed that the developed method has high sensitivity (limit of detection: 0.0004~0.7609 mg/kg) and accuracy (recovery: 80.10%~119.97%). A total of 65 chemical constituents were detected in the actual tea samples, and the content of each compound in different types of tea and by-products varied greatly (86622.93 ~ 219652.94 mg/kg). The compounds including epicatechin (2399.42 ~ 21207.83 mg/kg), epigallocatechin (1369.47~7934.14 mg/kg), epicatechingallate (6484.68~26854.46 mg/kg), epigallocatechingallate (6484.68 ~ 28844.07 mg/kg), theogallin (2230.36 ~ 14991.11 mg/kg), theanine (5901.84 ~ 14458.35) mg/kg), caffeine (6506.29-12017.14 mg/kg), quinic acid (5649.48-29529.46 mg/kg) showed relative high contents. Compared with tea samples, the tea by-products including yellow leaves and tea residue also contain higher contents of caffeine, catechin and theanine, indicating the potential value of these by-products.

Key words: Tea, Chemical constituents, Glycerin, Extraction, Mass spectrometry, Quantitation