title: Rapid assay of vitamin E in vegetable oils by reversed-phase capillary electrochromatography.
abstract: A rapid capillary electrochromatographic (CEC) method for the analysis of vitamin E in vegetable oils is reported. Vitamin E consists of a group of eight isomers, tocopherols (TOHs) and tocotrienols. The separation of four TOHs (alpha-, gamma-, delta-TOH), alpha-tocopherol acetate (alpha-TOH-Ac), and an antioxidant compound, butylated hydroxytoluene (BHT) used to prevent TOH autoxidation, was optimized. The CEC experiments were carried out in a 75 microm inner diameter (ID) fused-silica capillary, partially packed with 3 microm C(18 )stationary phase (33 cm total length, 8.4 cm and 7 cm effective and packed lengths, respectively). The optimum mobile phase was a polar organic phase composed of a mixture of methanol-acetonitrile in the ratio 50/50 v/v containing 0.01% ammonium acetate, applying a voltage and temperature set at -25 kV and 20 degrees C, respectively. The tocopherols and the BHT were successfully separated within 2.5 min using the short-end injection method. Under these experimental conditions, repeatability of retention time and peak area, analyte detection and quantitation limits, linearity, precision, and accuracy were studied. The CEC method was applied to determine the content of TOHs in different commercially available oils of virgin olive, hazelnut, sunflower, and soybean. The extraction of vitamin E isomers from oil samples was achieved using methanol and a methanol-isopropanol mixture.
authors.affiliation: Istituto di Metodologie Chimiche, CNR, Area della Ricerca di Roma 1, Monterotondo Scalo, Rome, Italy.
authors.forename: Zeineb
authors.initials: Z
authors.lastname: Aturki
authors.affiliation: Istituto di Metodologie Chimiche, CNR, Area della Ricerca di Roma 1, Monterotondo Scalo, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: D'Orazio
authors.affiliation: Istituto di Metodologie Chimiche, CNR, Area della Ricerca di Roma 1, Monterotondo Scalo, Rome, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Fanali
mesh_terms: D002084:Butylated Hydroxytoluene / Q000302:isolation & purification; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D010938:Plant Oils / Q000737:chemistry*; D015203:Reproducibility of Results; D014810:Vitamin E / Q000032:analysis*
chemical_list: D010938:Plant Oils; D014810:Vitamin E; D002084:Butylated Hydroxytoluene