Analytical Sciences

Simultaneous Determination of Tocopherols and Tocotrienols in Hazelnuts by a Normal Phase Liquid Chromatographic Method

Joana S. AMARAL,*^1,*² Susana CASAL,*³ Duarte TORRES,*⁴ Rosa M. SEABRA,*¹ and Beatriz P. P. OLIVEIRA*³

*1 REQUIMTE, Serviço de Farmacognosia, Faculdade de Farmácia, Rua Aníbal Cunha, 164, 4099-030 Porto, Portugal
*2 Escola Superior de Tecnologia e de Gestão, Instituto Politécnico de Bragança, Quinta de Sta. Apolónia, Apartado 134, 5301-857 Bragança, Portugal
*3 REQUIMTE, Serviço de Bromatologia, Faculdade de Farmácia, Rua Aníbal Cunha, 164, 4099-030 Porto, Portugal
*4 REQUIMTE, Departamento de Engenharia Química, Faculdade de Engenharia, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal

A normal-phase high-performance liquid chromatography (NP-HPLC) method for the determination of tocopherols and tocotrienols in hazelnuts is reported. Three extraction procedures (with and without saponification) were assayed; the best results were obtained with a simple solid-liquid extraction procedure. Chromatographic separation was achieved using an Inertsil 5 SI column using isocratic elution with hexane/1,4-dioxane (95.5:4.5, v/v) at a flow rate of 0.7 mL/min. The effluent was monitored by a series arrangement of a diode-array followed by a fluorescence detector. All compounds were separated in a short period of time (17 min). The method proved to be rapid, sensitive, reproducible and accurate, allowing the simultaneous determination of all vitamin E homologues.

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