Determination of aliphatic alcohols, squalene, α-tocopherol and sterols in olive oils:: direct method involving gas chromatography of the unsaponifiable fraction following silylation

In general, analyses for aliphatic alcohols, sterols and tocopherols in vegetable oils are performed separately. A simple and reliable procedure is presented for the quantification of the alkanols, squalene, alpha -tocopherol and sterols in olive oils by a direct method involving gas chromatographic (GC) analysis of the unsaponifiable fraction after silylation. The method eliminates the need for a preliminary thin-layer chromatographic (TLC) fractionation prior to GC. External standard calibration with reference substances was used for the quantification of squalene, alpha -tocopherol and sterols and internal standard calibration for the quantification of aliphatic alcohols. The analyte recovery and the repeatability of the quantitative results were evaluated and were acceptable for routine use.