title: Virgin olive oil ortho-phenols--electroanalytical quantification.
abstract: An electroanalytical methodology was developed for the determination of the total ortho-phenol content of virgin olive oil (VOO) with high sensitivity and reproducibility. The VOO ortho-phenol content depends on its freshness and is normally expressed as HT equivalent. Screen-printed electrodes were used with cyclic voltammetry to investigate the oxidation of catechol, phenol, hydroxytyrosol (HT), tyrosol, caffeic acid and ferulic acid. The oxidation of ortho-phenols and mono-phenols occurs following different mechanisms, and at different potentials. Using screen-printed electrodes and square wave voltammetry, an HT detection limit of 0.40 μM, was obtained. The electroanalytical methodology developed was applied to the determination of ortho-phenol content in fresh and old VOO. The HT equivalent determined for a two-year-old VOO sample was 3mg/kg, for one-year-old samples was 6-7 mg/kg, and for a fresh VOO sample 30 mg/kg, recoveries in the range of 78-93% of HT standard being obtained. The effect of VOO matrix components on the HT standard response was investigated.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
authors.forename: Teodor Adrian
authors.initials: TA
authors.lastname: Enache
authors.forename: Aziz
authors.initials: A
authors.lastname: Amine
authors.forename: Christopher M A
authors.initials: CM
authors.lastname: Brett
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Oliveira-Brett