Tocopherol Content in Vegetable Oils Using a Rapid HPLC Fluorescence Detection Method

Abstract

A quick and direct method based on reversed phase high performance liquid chromatography with fluorescence detector for measuring tocopherols (α , β + γ and δ) has been developed. Oils are diluted in methanol: hexane: tetrahydrofuran (neither previous extraction of tocopherols nor saponification procedure are required) and after being vortexed and centrifuged, an aliquot of the overlay was injected directly into an Alltima C 18 column. Acetonitrile and methanol (50: 50) mixture was used as a mobile phase with a flow rate of 1 mL min-1. Quantification of tocopherols was performed by fluorescence detector at 290 nm excitation wavelength and 325 nm emission wavelength. Tocopherols were separated at 25°C in less than 10 min after injection. The method has good limit of detection (9 ng g-1 for α-tocopherol and 8 ng g-1 for β-, γ- and δ- tocopherols) and reproducibility (CV< 2.9 %). This method can be used to assess the influence of genetic modification of oil seeds on the distribution of tocopherols or the effect of tocopherols on the oxidative stability of edible plant oils.