Evaluation of α-tocopherol in virgin olive oil by a luminiscent method

Natural fluorophores such as tocopherols are of great importance for the characterization and authentication of virgin olive oil. The band of the luminescent spectrum which is most accurately associated with the presence of alpha-tocopherol (380-420 nm) at lambda(exc) = 350 nm was detected and its precision was evaluated once the analytical process was optimized. A virgin olive oil, cv. Comicabra, was spiked with several quantities of alpha-tocopherol, from 25 mg/Kg to 1200mg/Kg, to build a ridge regression model (adjusted-R-2 = 0.99) based on five wavelengths (370, 371, 378, 414 and 417 nm) which are attributed to the fluorescence of this compound. The tentative model was validated (adjusted-R-2 = 0.87) with 8 samples of a virgin olive oil, cv. Picual, spiked with amounts of alpha-tocopherols ranging from 25 mg/kg to 250mg/kg. Finally, the model was successfully validated with 7 monovarietal virgin olive oils from various olive producing countries (adjusted - R-2 = 0.92).