title: Multicommuted flow injection method for fast photometric determination of phenolic compounds in commercial virgin olive oil samples.
abstract: A multicommuted flow injection method has been developed for the determination of phenolic species in virgin olive oil samples. The method is based on the inhibitory effect of antioxidants on a stable and colored radical cation formation from the colorless compound N,N-dimethyl-p-phenylenediamine (DMPD(•+)) in acidic medium in the presence of Fe(III) as oxidant. The signal inhibition by phenolic species and other antioxidants is proportional to their concentration in the olive oil sample. Absorbance was recorded at 515nm by means of a modular fiber optic spectrometer. Oleuropein was used as the standard for phenols determination and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) was the reference standard used for total antioxidant content calculation. Linear response was observed within the range of 250-1000mg/kg oleuropein, which was in accordance with phenolic contents observed in commercial extra virgin olive oil in the present study. Fast and low-volume liquid-liquid extraction of the samples using 60% MeOH was made previous to their insertion in the flow multicommuted system. The five three-way solenoid valves used for multicommuted liquid handling were controlled by a homemade electronic interface and Java-written software. The proposed approach was applied to different commercial extra virgin olive oil samples and the results were consistent with those obtained by the Folin Ciocalteu (FC) method. Total time for the sample preparation and the analysis required in the present approach can be drastically reduced: the throughput of the present analysis is 8 samples/h in contrast to 1sample/h of the conventional FC method. The present method is easy to implement in routine analysis and can be regarded as a feasible alternative to FC method.
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, E-23071 Jaén, Spain; Centro de Estudios Avanzados en Olivar y Aceite de Oliva (CEAOAO), University of Jaén, Parque Científico Tecnológico Geolit, E-23620 Mengíbar, Jaén, Spain.
authors.forename: Felipe J
authors.initials: FJ
authors.lastname: Lara-Ortega
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, E-23071 Jaén, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Sainz-Gonzalo
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, E-23071 Jaén, Spain.
authors.forename: Bienvenida
authors.initials: B
authors.lastname: Gilbert-López
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, E-23071 Jaén, Spain; Centro de Estudios Avanzados en Olivar y Aceite de Oliva (CEAOAO), University of Jaén, Parque Científico Tecnológico Geolit, E-23620 Mengíbar, Jaén, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: García-Reyes
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, E-23071 Jaén, Spain; Centro de Estudios Avanzados en Olivar y Aceite de Oliva (CEAOAO), University of Jaén, Parque Científico Tecnológico Geolit, E-23620 Mengíbar, Jaén, Spain. Electronic address: amolina@ujaen.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina-Díaz
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D017022:Flow Injection Analysis; D000069463:Olive Oil / Q000032:analysis*; D016877:Oxidants / Q000737:chemistry; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D010655:Phenylenediamines / Q000737:chemistry*; D010783:Photometry
chemical_list: D000975:Antioxidants; D002712:Chlorides; D005290:Ferric Compounds; C000603232:N,N-dimethyl-p-phenylenediamine; D000069463:Olive Oil; D016877:Oxidants; D010636:Phenols; D010655:Phenylenediamines; C024555:ferric chloride
keywords: Antioxidants; Flow injection analysis; Folin–Ciocalteu; Multicommutation; Olive oil; Phenolic compounds determination