title: A novel multicommuted fluorimetric optosensor for determination of resveratrol in beer.
abstract: Resveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin that plays a central role in the human diet because of its antioxidant, anticarcinogenic and antimutagenic properties. This paper shows the development of a multicommuted optosensing device for the determination of resveratrol in beer. The method is based on the measurement of the fluorescence (277/382 nm, λ(ex)/λ(em)) of the photoproduct on-line generated by UV-irradiation of resveratrol. The fluorescent photoproduct is monitored once it is retained on a solid support (Sephadex QAE A-25) in the detection area, which improves both sensitivity and selectivity. The sample was delipidated with toluene and cyclohexane and resveratrol was extracted by solid-phase extraction (SPE) on C(18) cartridges, using methanol as eluent. This pre-treatment allowed recovering about an 82% resveratrol and removing its 3-O-β-d-glycoside (piceid) and other interfering substances present in beer. The method provides a detection limit (DL) of 1.0 ng mL(-1) and a linear dynamic range (LDR) of 3.3-100 ng mL(-1). It was satisfactorily applied to the determination of resveratrol in top- and bottom-fermented beers by standard addition calibration. Resveratrol concentrations in the analysed samples varied from 4.1 to 14.1 ng mL(-1). This is the first proposed spectroscopic method for determination of resveratrol in beer.
authors.affiliation: Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas s/n, 23071 Jaén, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: Molina-García
authors.forename: Antonio
authors.initials: A
authors.lastname: Ruiz-Medina
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Fernández-de Córdova
mesh_terms: D001515:Beer / Q000032:analysis*; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D017022:Flow Injection Analysis; D005470:Fluorometry / Q000379:methods*; D005504:Food Analysis / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D000077185:Resveratrol; D052616:Solid Phase Extraction; D013267:Stilbenes / Q000032:analysis* / Q000302:isolation & purification; D013997:Time Factors
chemical_list: D013267:Stilbenes; D000077185:Resveratrol