2 cyclopentenone

Authentic standards were obtained from commercial sources: 3-methylbutanal, hexanal, furfural, heptanal, octanal, phenylacetaldehyde, α-pinene, 5-methyl-2-furancarboxaldehyde, nonanal, decanal, ethanol, 1-propanol, 2-butanol, 3-methyl-1-butanol, propylene glycol, 1-pentanol, 2-furanmethanol, 1-hexanol, phenol, 2-methylphenol, 4-methylphenol (p-cresol), 3-methylphenol, 2-methoxyphenol, 2,6-dimethylphenol, 2-methoxy-3-methylphenol, creosol, 4-ethyl-2-methoxyphenol, 2-methoxy-4-vinylphenol, 2,6-dimethoxyphenol, octane, eugenol, trans-isoeugenol, 1-hydroxy-2-propanone, 2-cyclopentenone, cyclooctane, 2-methyl-2-cyclopentenone, 3,4-dimethyl-2-cyclo-pentenone, benzoic acid, 2-hydroxy-3-methyl-2-cyclopentenone, 3-methyl-2-cyclopentenone, acetic acid, 2,3-dimethyl-2-cyclopentenone, 3-ethyl-2-cyclopentenone, butanoic acid, styrene, 3-ethyl-2-hydroxy-2-cyclopentenone, 2,3,4-trimethylpentane, 2-furylmethylketone 2,3,3-trimethylpentane, 2,2,8-trimethyldecane, propanoic acid, 3-methyl-3-heptene, (Z)-2-octene, d-limonene, and ethyl hexanoate were purchased from Sigma-Aldrich (Shanghai, China). 2-Octanol (internal standard) and n-alkane standards (C₆–C₃₀) were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). All substances are AR, at least 97% purity. The purification system from Milli-Q (Millipore, Bedford, MA, USA) to obtain purified water.