title: Development and validation of an HPLC-method for determination of free and bound phenolic acids in cereals after solid-phase extraction.
abstract: Whole cereal grains are a good source of phenolic acids associated with reduced risk of chronic diseases. This paper reports the development and validation of a high-performance liquid chromatography-diode array detection (HPLC-DAD) method for the determination of phenolic acids in cereals in either free or bound form. Extraction of free phenolic acids and clean-up was performed by an optimised solid-phase extraction (SPE) protocol on Oasis HLB cartridges using aqueous methanol as eluant. The mean recovery of analytes ranged between 84% and 106%. Bound phenolic acids were extracted using alkaline hydrolysis with mean recoveries of 80-95%, except for gallic acid, caffeic acid and protocatechuic acid. Both free and bound phenolic extracts were separated on a Nucleosil 100 C18 column, 5 μm (250 mm × 4.6 mm) thermostated at 30 °C, using a linear gradient elution system consisting of 1% (v/v) acetic acid in methanol. Method validation was performed by means of linearity, accuracy, intra-day and inter-day precision and sensitivity. Detection limits ranged between 0.13 and 0.18 μg/g. The method was applied to the analysis of free and bound phenolic acids contents in durum wheat, bread wheat, barley, oat, rice, rye, corn and triticale.
authors.affiliation: Cereal Institute, National Agricultural Research Foundation, P.O. Box 60411, Thessaloniki 57 001, Greece.
authors.forename: Maria N
authors.initials: MN
authors.lastname: Irakli
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54 124, Greece.
authors.forename: Victoria F
authors.initials: VF
authors.lastname: Samanidou
authors.affiliation: Laboratory of Food Chemistry and Biochemistry, Department of Food Science and Technology, Aristotle University, P.O. Box 235, Thessaloniki 54 124, Greece.
authors.forename: Costas G
authors.initials: CG
authors.lastname: Biliaderis
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54 124, Greece.
authors.forename: Ioannis N
authors.initials: IN
authors.lastname: Papadoyannis
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002523:Edible Grain / Q000737:chemistry*; D062385:Hydroxybenzoates / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*
chemical_list: D062385:Hydroxybenzoates; C017616:phenolic acid