Tocopherol speciation as first screening for the assessment of extra virgin olive oil quality by reversed-phase high-performance liquid chromatography/fluorescence detector

A method based on reversed phase high-performance liquid chromatography with fluorescence detector has been developed for the determination of tocopherols in vegetable oils Oils were diluted in acetonitrile/tetrahydrofuran (THF) and injected directly onto HyPurity C-18 column Methanol and THF (90 10) mixture was used as a mobile phase Tocopherols were detected by fluorescence detector The method had good limit of detection (LOD) (7 ng/g for alpha-tocopherol and 6 ng/g for beta- gamma- and delta tocopherols) and reproducibility (CV% < 2 8%) The method was applied to the determination of alpha- (beta+gamma) and delta tocopherols in extra virgin olive oil (EVOO) sunflower high oleic sunflower oil (HOSO) hazelnut soy corn peanut and almond oil A new parameter the ratio of alpha-/(beta+gamma)-tocopherol concentration (named alpha/beta tocopherol ratio) in these vegetable oils was systematically assessed and proposed as a first screening marker of the authenticity of EVOO by studying EVOO/sunflower EVOO/hazelnut and EVOO/peanut mixtures The use of delta-tocopherol as adulteration marker was also discussed (C) 2010 Elsevier Ltd All rights reserved