UPLC method for the determination of vitamin E homologues and derivatives in vegetable oils, margarines and supplement capsules using pentafluorophenyl column

A sensitive and rapid reversed-phase ultra performance liquid chromatographic (UPLC) method for the simultaneous determination of tocopherols (alpha-, beta-, gamma-, delta-), tocotrienols (alpha-, beta-, gamma-, delta-), alpha-tocopherol acetate and alpha-tocopherol nicotinate is described. The separation was achieved using a Kinetex pentafluorophenyl (PFP) column (150 x 2.1 mm, 2.6 mu m) with both photodiode array (PDA) and fluorescence (FL) detectors that were connected in series. Column was thermostated at 42 degrees C. Under a gradient system consisting of methanol and water at a constant flow rate of 038 mL min(-1), all the ten analytes were well separated in less than 9.5 min. The method was validated in terms of linearity, limits of detection and. quantitation, precision and recoveries. Calibration curves of the ten compounds were well correlated (r(2) > 0.999) within the range of 100 to 25,000 mu g L-1 for alpha-tocopherol acetate and a-tocopherol nicotinate, 10 to 25,000 mu g L-1 for a-tocotrienol and 5 to 25,000 mu g(-1) for the other components. The method is simple and sensitive with detection limits (SIN, 3) of 1.0 to 3.0 mu g L-1 (FL detection) and 30 to 74 mu g L-1 (PDA detection). Relative standard deviations for intra- and inter-day retention times ( < 1%) and peak areas ( <= 4%) were obtained. The method was successfully applied to the determination of vitamin E in vegetable oils (extra virgin olive, virgin olive, pomace olive, blended virgin and refined olive, sunflower, soybean, palm olein, carotino, crude palm, walnut, rice bran and grape seed), margarines and supplements. (C) 2014 Elsevier B.V. All rights reserved.