Lc ms grade acetonitrile

DPPH, ABTS, TPTZ (2,4,6-tri-2-pyridinyl-1,3,5-triazine), and Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) were purchased from Sigma (St. Louis, MO, USA), and methanol, ethanol, petroleum ether, ethyl acetate, n-butanol, and other reagents for the antioxidant test were analytically pure and purchased from China National Pharmaceutical Group Co. (Beijing, China). Rutin (lot no. 100080–201805, HPLC ≥98%), astragaloside (lot no. 110781–201908, HPLC ≥98%), isoquercetin (lot no. 111809–201804, HPLC ≥98%), quercetin (lot no. 100081–201610, HPLC ≥98%), kaempferol (lot no. 110861–201703, HPLC ≥98%), and kaempferol-3-o-rutoside (lot no. 112007–201903, HPLC ≥98%) standard reference materials were obtained from National Institutes for Food and Drug Control (Beijing, China). Chromatography grade and LC-MS grade acetonitrile were obtained from Tedia (Fairfield, OH, USA) and Fisher (Waltham, MA, USA), respectively.
The rhizome of Tetrastigma hemsleyanum Diels et Gilg from Guangxi Province, China, was purchased from Guangxi, China (lot no. 180615), and identified by Professor Xia Miao-fen at Zhejiang Pharmaceutical College.

l-Glycine (Gly), alanine (Ala), γ-aminobutyric acid (GABA), l-aspartic acid (Asp), l-glutamic acid (Glu), L-methionine (Met), l-phenylalanine (Phe), tyrosine (Tyr), d-serine (d-Ser), homocysteine (Hcy), N-acetylaspartic acid (Naa), and tryptophan (Trp) were purchased from Sigma Aldrich Co., Ltd. (Shanghai, China). Formic acid (purity 99%) was obtained from Roe Scientific Inc. (Newark, DE, USA). All solutions were prepared using LC-MS Ultra High Purity water and LC-MS-grade acetonitrile (Tedia Company Inc., Fairfield, OH, USA). The I.S. (acrylamide-d₃) was purchased from Toronto Research Chemicals Inc. (Toronto, ON, Canada).
Galangin with 98.0% purity was purchased from Nanjing Zelang Medical Technology Co., Ltd (Nanjing, China). The stock solution was prepared by dissolving the galangin power in sterile saline (containing 5% polysorbate 80). EGb761 (Folium Ginkgo Extract), used as a positive control to explore the efficacy of galangin, was purchased from Dr. Willmar Schwabe (Karlsruhe, Germany).