α cholestanol

Potassium iodide, glacial acetic acid, chloroform, sodium thiosulfate, sodium hydroxide, starch, β-carotene, α-tocotrienol, α-tocopherol, and α-cholestanol were purchased from Sigma Aldrich (Milan, Italy). Petroleum ether, diethyl ether, ethanol, tetrahydrofuran, n-hexane, citric acid, and sodium sulfate anhydrous were purchased from Carlo Erba (Rodano, Italy). Bleaching earth was purchased from Clariant (Milan, Italy).

All chemicals and reagents were obtained from Sigma-Aldrich Chemical Co., Ltd. (Milan, Italy). The isooctane (2,2,5 tri-methyl-pentane), n-heptane, n-hexane, and diethyl ether were of analytical grade. Internal standards α-cholestanol and cholesteryl palmitate were purchased from Sigma-Aldrich (Milan, Italy). Internal standards were prepared weekly using n-heptane as the diluting solvent. All solutions were stored at 4 °C. Silica gel (pore size 60 Å, 0.04–0.015 µm particle size) was purchased from Agilent (Milan, Italy).

Commercial standards of myrtenyl acetate, 1,8-cineole, p-cymene, (+)-α-pinene, (−)-β-pinene, γ-terpinene, (R)-(−)-α-phellandrene, carvacrol, (+)-carvone, camphene, 3-carene, geraniol, o-cymene, and a mixture of α-fenchyl acetate and alkane standard solution C7-C30 were obtained from Sigma Aldrich (St. Louis, MO, USA); α-terpineol, myrcene, linalool, butyl butyrate, and eugenol from Merck (Darmstadt, Germany); R-(+)-limonene and nerol from Fluka^® Analytical (Munich, Germany); and α-terpinene from Dr. Ehrenstorfer GmbH (Augsburg, Germany). Reagents for silylation, α-cholestanol, campesterol, stigmasterol, and β-sitosterol were purchased from Sigma Aldrich (St. Louis, MO, USA). The standard mixture of 37 fatty acid methyl esters (Supelco™ 37 Component FAME Mix) was obtained from Sigma-Aldrich (St. Louis, MO, USA). Aluminum oxide, sodium hydroxide, sodium chloride, and sodium hydrogen sulfate monohydrate were procured from Merck KgaA (Darmstadt, Germany). Diethyl ether, anhydrous ethanol, ethyl acetate, and methanol were acquired from Carlo Erba Reagents GmbH (Emmendingen, Germany). Isooctane, isopropanol, potassium hydroxide, 96% ethanol, and n-hexane were obtained from J. T. Baker (Phillipsburg, NJ, USA).