E 2 hexen 1 ol

A mixture of n-alkanes (C6–C10) dissolved in pentane was purchased from Fluka (Buchs, Switzerland) and α-pinene (≥95%) from Merck. All other reference compounds were supplied by Sigma-Aldrich (Munich, Germany): (E)-2-hexen-1-ol (≥ 95%), (E)-2-octenal (≥94%), (E)-2-nonenal (≥93%), hexyl acetate (99%), 1-decyne (98%), (Z)-3-hexenyl acetate (≥98%), (E)-2-decenal (analytical standard), 3-methyl-1-butanol acetate (isoamyl acetate) (≥97%), benzaldehyde (≥99%), nonanal (97%), (E)-2-hexenal (98%), (E)-2-octen-1-ol (97%), decanal (≥98%), 2,4-octadienal (96%), (E,E)-2,4-decadienal (analytical standard), (R)-(+)-limonene (97%), (E,E)-2,4-hexadienal (≥95%). Dichloromethane (anhydrous, ≥99.8%) and pentane (anhydrous, ≥99%) used as diluents were also from Sigma-Aldrich.
Samples of the reference compounds were prepared by dilution of the individual compounds in Dichloromethane, except for a mixture of alkanes which were diluted in pentane. The concentration of stock solutions of each compound was 0.1 mg mL⁻¹ but the final dilution of each standard was individually modified to obtain good reproducibility of retention times.

The external C6 volatile standards, including hexanal (98.0% purity), (E)-2-hexenal (98.0%), 1-hexanol (99.0%), (E)-2-hexen-1-ol (96.0%), (E)-3-hexen-1-ol (98.0%), (Z)-2-hexen-1-ol (96.0%), (Z)-3-hexen-1-ol (98.0%), ethyl hexanoate (99.0%), hexyl acetate (99.0%), (Z)-3-hexen-1-acetate (98.0%), and hexanoic acid (99.0%), were purchased from Sigma-Aldrich (St. Louis, MO, USA). The internal standard 4-methyl-2-pentanol was also purchased from Sigma-Aldrich, with a purity of 98.0%. Water used in this study was purified from a Milli-Q purification system (Millipore, Bedford, MA, USA). Polyvinylpolypyrrolidone (PVPP) was a product of Sigma-Aldrich. SYBR^® Premix Ex TaqTM and Spectrum™ Plant Total RNA Kit were purchased from TaKaRa Bio (Otsu, Shiga, Japan) and Sigma-Aldrich, respectively. A reverse transcription system kit was obtained from Promega (Madison, WI, USA). Other reagents used in this study were purchased from the Beijing Chemical Works (Beijing, China).

Acetonitrile, formic acid, and methanol were purchased from Fisher Company (Fairlawn, NJ, USA). D-(+)-dextronic acid δ-lactone was purchased from Sigma-Aldrich (St. Louis, MO, USA). The Cleanert^® PEP-SPE resin (150 mg/6 mL) was obtained from Bonna-Agela (Wilmington, DE, USA).
The standards (purities > 95%) used for identification and quantification of the volatile compounds 1-hexanol, (E)-2-hexen-1-ol, (Z)-2-hexen-1-ol, (E)-3-hexen-1-ol, (Z)-3-hexen-1-ol, hexanal, (E)-2-hexenal, 1-nonanol, furfural, hexanoic acid, limonene, D-limonene, myrcene, linalol, α-terpineol, 4-terpineol, β-citronellol, citral, geranylacetone, geraniol, nerol, cis-furan oxidin, spirulina, (Z)-orange sterol, (E)-β-damascenone, (E)-β-ionone, and 4-methyl-2-pentanol were all supplied by Sigma-Aldrich (St. Louis, MO, USA). The deionized water (<18 WΩ resistance) was obtained through a Milli-Q Element water purification system (Millipore, Bedford, MA, USA). All the other chemicals or reactives without especial mention were purchased from Beijing Chemical Works (Beijing, China).