Methyl vanillate

Human serum albumin (HSA) fatty acid free and essentially globulin free (A3782), bovine serum albumin (BSA) fatty acid free and essentially globulin free (A7030), methyl vanillate, 2,4,6-tri(2-pyridyl)-S-triazine (TPTZ), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH), 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (pyranine), potassium persulfate, ammonium ferrous sulfate hexahydrate, warfarin, ibuprofen, dansylglycine, and phenylbutazone were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Stock solutions of warfarin, ibuprofen, phenylbutazone, methyl vanillate and its dimer dimethyl divanillate (10 mmol L⁻¹) were prepared in dimethyl sulfoxide. From the stock solutions, working solutions (1 mmol L⁻¹ or less) were prepared in 50 mmol L⁻¹ phosphate buffer at pH 7.0. HSA was dissolved in 50 mmol L⁻¹ phosphate buffer at pH 7.0 to give a 1 mmol L⁻¹ stock solution.

LiChrolut EN cartridges (500 mg, 6 mL) were obtained from Merck (Darmstadt, Germany). All chemicals were of analytical reagent grade unless otherwise stated, and water was obtained from a Milli-Q purification system (MilliporeSigma, Burlington, MA, USA). Folin-Ciocalteu reagent, sodium carbonate, sodium acetate, potassium chloride, sodium chloride, sucrose, methanol (HPLC grade), ethanol (HPLC grade), dichloromethane (HPLC grade) and gallic acid were purchased from SCR^® (Shanghai, China). Eucalyptol (99%), linalool (≥95%), (−)-myrtenol (95%), carveol (97%, mixture of isomers), borneol, (≥99.0%, sum of enantiomers, GC), terpinolene (≥94.0%), β-citronellol (95%), geraniol (98%), ethyl-2-methylbutyrate (99%), ethyl-3-methylbutyrate (98%), (Z)-3-hexenol (98%), (E)-2-hexenol (96%), benzyl alcohol (≥99%), phenylethyl alcohol (≥99%), cuminic alcohol (97%), methyl butanoate (99%), isobutyl acetate (99%), ethyl butanoate (99%), isoamyl acetate (≥99%), methyl benzoate (99%), ethyl benzoate (≥99%), diethyl succinate (99%), methyl salicylate (≥99%), ethyl octanoate (≥99%), ethyl decanoate (98%), methyl vanillate (99%), decanoic acid (≥98.0%), benzaldehyde (≥99%), p-cresol (99%), 4-vinylguaiacol (≥98.0%), vanillin (99%), (E)-asarone (98%), (Z)-asarone (70%) were obtained from Sigma-Aldrich (St. Louis, MO, USA). All volatile standards were prepared by dilution with HPLC grade methanol.