Tetradecane

For the determination of the retention indices (RI) of the separated compounds, the following hydrocarbons were used: nonane (≥99%), decane (≥99%), undecane (≥99%), dodecane (99%), tridecane (≥99%), tetradecane (≥99%), and hexadecane (≥99%) purchased from Merck KGaA (Darmstadt, Germany). Hexane (Thermo Fisher Scientific GmbH, Bremen, Germany) was used for the dilution of the EO.

The following hydrocarbons were used to determine the retention indices (RIs): nonane (99%), decane (≥99%), undecane (≥99%), dodecane (99%), tridecane (≥99%), tetradecane (≥99%), hexadecane (≥99%), heptadecane (99%), octadecane (99%), nonadecane (99%), eicosane (99%), heneicosane (≥99.5%), tricosane (99%), tetracosane (99%), pentacosane (99%), octacosane (99%), and triacontane (99%), and they were purchased from Merck KGaA (Darmstadt, Germany). GC-grade hexane was used for diluting the essential oils, purchased from Thermo Fisher Scientific GmbH (Bremen, Germany). Fluorescein (3′,6′-dihydroxy-3H-spiro [2-benzofuran-1,9′-xanthen]-3-one) (CAS 2321-07-5), AAPH (2,2′-azobis-(2-methylpropionamidine)-dihydrochloride) (CAS 2997-92-4), and trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) (CAS 53188-07-1) were purchased from Sigma-Aldrich (Darmstadt, Germany).

Lipases from T. lanuginosus (2,200 U/mL, Sigma), R. oryzae (Aldrich, product number 80612), R. arrhizus (Sigma, product number 62305), P. fluorescens (Aldrich), R. miehei (Sigma), Pseudomonas species (Aldrich) and Candida antarctica lipase B (Sigma), p-nitrophenyl butyrate and silica gels of different particle sizes (silica gel 35 to 79 μm, silica fumed 0.2 to 0.3 μm and silica fumed 0.007 μm) were obtained from Sigma-Aldrich Co. (Steinheim, Germany); cyclohexane and tetradecane were purchased from Merck (Darmstadt, Germany); n-heptane, ethanol (99.5%) from VWR (Stockholm, Sweden); and N-methyl-N-trimethylsilylheptafluorobutyramide (MSHFBA, Machery-Nagel) from ScantecLab (Partille, Sweden). Triolein was obtained from Larodan Fine Chemicals (Malmö, Sweden), perfluorodecyltriethoxysilane from Alfa Aesar and phenyltrimethoxysilane and n-octyltriethoxysilane were acquired from Acros Organics. Rapeseed oil was purchased in a local supermarket. Other chemicals were of analytical grade. A high oleic acid content starting material was used in order to simulate a low-quality oil. The composition (molar ratio) of the starting material was 54% Triolein, 24% DAGs and 22% oleic acid.

For determination of retention indices (RIs), heptane (99%), octane (≥99%), nonane (99%), decane (≥99%), undecane (≥99%), dodecane (99%), tridecane (≥99%), tetradecane (≥99%), hexadecane (≥99%), heptadecane (99%), octadecane (99%), nonadecane (99%), and eicosane (99%) purchased from Merck KGaA (Darmstadt, Germany) were used. For diluting essential oils, hexane purchased from Thermo Fisher Scientific GmbH (Bremen, Germany) was used.

Solvents with reagent grade (i.e., n-heptane, n-hexane, diethyl ether, and methanol) were purchased from J.T. Baker (Phillipsburg, NJ, USA), while solvents with HPLC grade (i.e., n-hexane, ethyl acetate, methanol, and water) were supplied by LiChrosolv (Merk, Darmstadt, Germany). Reagents with a trace metal analysis grade [i.e., H₂O₂ (30% v/v) and HNO₃ (65% v/v)] and ultrapure water (resistivity of 10 mΩ cm) were purchased from J.T. Baker (Milan, Italy). The Folin–Ciocalteu reagent was from Sigma-Aldrich (Steinheim, Germany). Fatty acid methyl esters (FAMEs) reference standards (C4–C24) and commercial standards of single tocopherols (i.e., α-tocopherol, γ-tocopherol, and δ-tocopherol, 98% purity each), gallic acid (≥99% purity), and squalene (≥98% purity) were purchased from Supelco (Bellefonte, PA, USA). Stock solutions of Na, Mg, K, Fe, Cu, Mn, Zn, Se, Ni, Cr, Al, As, Cd, and Pb (1000 mg/L in 2% HNO₃, each) were provided by Fluka (Milan, Italy). Depending on the targeted analyte, the internal standards employed for the normalization of the calibration procedure were: tetradecane (99% purity, Sigma-Aldrich) and rhenium (1000 µg/mL in 5% HNO₃, LGC Standards).

Allyl-alcohol (99%), benzyl alcohol (99%), butanol (99.5%), 1-octanol (99%), phenyl acetaldehyde (98%, stabilized) and trimethylamine (99.7%) were purchased from Acros Organics. 1-Adamantyl isocyanide (95%), cyclohexanol (99%), cyclohexyl isocyanide (98%), 2-butanol (99.5%, anhydrous), 2,4-dinitrobenzaldehyde (97%), isobutyraldehyde (≥99.5%), 2-morpholinoethyl isocyanide (≥98%), tert-butanol (≥99.5%, anhydrous), tert-butyl isocyanide (98%), tetradecane (≥99.5%) and undecylenic aldehyde (95%) were obtained from Sigma Aldrich. Other chemicals used include: diazabicyclo[5.4.0]undec-7-ene (DBU, TCl, >98%), deuterated chloroform (CDCI₃-d, Merck), dimethyl sulfoxide (DMSO, VWR, 99%) and trimethyl acetaldehyde (ABCR, 97%). Carbon dioxide (CO₂) with purity over 99.9% was obtained from Air Liquide. Cyclohexane, ethyl acetate and dichloromethane were distilled before usage, while tetrahydrofuran (THF) was of technical grade and used without further purification. All other chemicals were used as received from the supplier.