Geranial

Methanol (HPLC grade) was purchased from Merck (Darmstadt, Germany) NaCl (analytical grade) was purchased from Sinopharm Chemical Reagent Co., Ltd (Beijing, China); and pure water was obtained from the Milli-Q purification system (Millipore, Bedford, MA).
The chemical standards were purchased as follows: (Z)-3-hexenal, 2-octanol, hexanal, (E)-2-hexenal, geranic acid, phellandrene, β-myrcene, β-damascenone, D-limonene, citronellol, benzyl alcohol, neral, α-terpineol, geranial, geraniol, rose oxide II (cis), rose oxide I (trans), phenylethyl alcohol from Sigma (St. Louis, MO, USA); octanoic acid, pentanal, octanal, nonanal, benzaldehyde, 3-methylbutanal, hexanoic acid, (Z)-3-hexenol, 1-octen-3-ol, heptanol, ethyl acetate, ethyl butyrate, ethyl isobutyrate, butyl acetate, ethyl pentanoate, methyl salicylate, hexyl acetate, (E)-2-hexenoic acid, P-cymene, terpinolene, linalool, 4-terpineol, geranyl acetone from Dr. Ehrenstorfer (Germany); β-ionone from Fluka (Buchs, Switzerland); ethyl hexanoate from Nu-chek (USA); octanol, hexanol, (E)-2-hexenol from Chem Service (USA), and n-alkanes (C₇-C₂₇) from Supelco (Bellefonte, PA).
The automatic solid-phase microextraction (SPME) fibres of 50/30 μm divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) were purchased from Supelco (Bellefonte, PA, USA).

Lemongrass (Cymbopogon flexuosus) and geranium Egyptian (Pelargonium graveolens) EOs were purchased from New Direction Aromatics (Mississauga, ON, Canada). Lemon eucalyptus (Eucalyptus citriadora) EO was purchased from Green Health (Lorton, VA, USA). Ethyl alcohol anhydrous (EtOH) was purchased from Commercial Alcohols (Greenfield Global, Brampton, ON, Canada). β-CD, hexane, tridecane, octanal, geranial, citronellal, and β-citronellol were purchased from Sigma-Aldrich (Oakville, ON, Canada).

Cinnamaldehyde (98% pure), a major constituent of C. verum EO, d-limonene (96% pure), a major constituent of C. aurantium EO, and geranial (96% pure), a major constituent of C. citratus EO together with standard n-alkanes (C₇–C₃₀) were supplied by Sigma-Aldrich company (USA). Temephos (1 ppm), the positive control, was obtained from Thailand’s Government Pharmaceutical Organization (GPO) (Pathum Thani, Thailand). Ethyl alcohol (95% v/v) was supplied by Thailand’s Liquor Distillery Organization (Chachoengsao, Thailand). All chemicals used in this study were reagent-grade.

Methanol HPLC grade from Merck (Darmstadt, Germany), NaCl (analytical grade) was obtained from Sigma–Aldrich (Millipore, Bedford, MA, USA) and pure water was obtained from the Milli-Q purification system (Millipore, Bedford, MA, USA). The standards (purity > 95%) used for the quantification and identification of the volatile compounds and the chemical standards were obtained as follows: (E)-2-hexenal, geranic acid, (Z)-3-hexenal, 2-octanol, hexanal, phellandrene, β-damascenone, β-myrcene, D-limonene, benzyl alcohol, citronellol, neral, geranial, α-terpineol, (Z)-rose oxide II, geraniol, (E)-rose oxide I and phenylethyl alcohol from Sigma (St. Louis, MO, USA); hexanoic acid, benzaldehyde, octanoic acid, octanal, nonanal, pentanal, 3-methylbutanal, 1-octen-3-ol, (Z)-3-hexenol, heptanol, ethyl butyrate, ethyl acetate, butyl acetate, ethyl pentanoate, ethyl isobutyrate, methyl salicylate, (E)-2-hexenoic acid, hexyl acetate, terpinolene, P-cymene, linalool, geranyl acetone, 4-terpineol, β-ionone and ethyl hexanoate was obtained from Nu-Chek Prep (Elysian, MN, USA); hexanol, octanol, (E)-2-hexenol from Chem Service Inc. (West Chester, PA, USA). The automatic solid phase microextraction (SPME) fibers of 50/30 μm divinylbenzene/polydimethylsiloxane/carboxen (DVB/PDMS/CAR) were obtained from Supelco (Bellefonte, PA, USA).