Phenethyl alcohol

The standards of volatile compounds were purchased from Sigma-Aldrich (St. Louis, MO, USA), including isobutanol, 3-methyl-1-butanol, cis-3-hexen-1-ol, 1-hexanol, heptanol, octanol, phenethyl alcohol, 2,6-nonadien-1-ol, dodecanol, ethyl acetate, isoamyl acetate, ethyl lactate, ethyl hexanoate, ethyl octanoate, diethyl succinate, phenethyl acetate, ethyl decanoate, butanoic acid, hexanoic acid, octanoic acid, dodecanoic acid, octanal, (2e,6z)-2,6-nonadienal, benzaldehyde, furfural, citronellol, linalool, rose oxide, geraniol, nerol, β-damascenone, β-ionone, nerolidol, hexanal, guaiacol, 4-Ethylphenol, and 2-octanol which were used as the internal standard.
Folin–Ciocalteu reagent and sodium chloride were purchased from Beijing Chemical Works (Beijing, China). Potassium hydrogen tartrate were purchased at Kemiou Chemical Reagent Co. (Tianjin, China). Bovine serum albumin was obtained from Asahi Kasei Corporation (Tokyo, Japan). Deionized water (<18 MW resistance) was purified by using a Milli-Q purification system (Molecular, Chongqing, China). Bentonite, soybean protein and potassium metabisulfite were purchased from Lallemand Company (Lallemand, Toulouse, France).

Sodium sulfide, methanethiol (MeSH), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), diisopropyl disulfide (DIDS), hexanoic acid, octanoic acid, phenethyl alcohol, 3-methyl-1-butanol, 2-methyl-1-propanol, ethyl acetate, 3-methyl-1-butyl acetate, ethyl hexanoate, and ethyl decanoate were from Sigma-Aldrich (St. Louis, MO, USA). Ethyl octanoate was from Eastman (Rochester, NY, USA). Methyl thioacetate (MeSOAc), ethyl thioacetate (EtSOAc), and diethyl sulfide (DES) were from Alfa-Aesar (Ward Hill, MA, USA). Ethyl methyl sulfide (EMS), dimethyl sulfide (DMS), diethyl disulfide (DEDS), methyl isopropyl sulfide (MIS), and ethyl isopropyl sulfide (EIS) were from TCI America (Portland, OR, USA). Methanol was from EMD Chemicals Inc. (Gibbstown, NJ, USA), l-tartaric acid from J.T. Baker (Phillipsburg, NJ, USA), and ethanol was from Koptec (King of Prussia, PA, USA).

Alginic acid, HPLC grade solvents (methanol, ethanol, dichloromethane, heptane), N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR), N-nitrosodi-n-propylamine (NDPA), N-nitrosopiperidine (NPIP), N-nitrosodi-n-butylamine (NDBA), carvone, linalool, linalyl acetate, syringol, resorcinol, guaiacol, vanillin, propanil, simazine, imazalil, acetochlor, chloropyrifos, thiobendazole, naphthalene, 1-naphthol, 1-napthylamine, aniline, imidazole, caffeine, phenethyl alcohol, furfural, methyl-2-furoate, and decanoic acid were purchased from Merck (Gillingham, Dorset, UK). These standards were dissolved in methanol at a concentration of 5 mg/mL of each nitrosamine. Working solutions were then prepared by an appropriate dilution of this stock solution with methanol. Stock solutions were protected from light and stored at 4 °C. Sodium hydroxide and hydrochloric acid were obtained from Thermo Fisher Scientific (UK).
C18 SPE cartridges (100 mg; 1 mL tube) were purchased from Merck (Gillingham, Dorset, UK). PGC SPE cartridges (100 mg; 1 mL) were obtained from Thermo Fisher Scientific (UK).