title: Development of a sample preparation method for the analysis of oxidized flavonols in onions and leek.
abstract: A method is presented for the determination of oxidized flavonols (i.e., hydroxybenzoylbenzofuranones) in plant material. Onions and leek are investigated using a newly developed solid-phase extraction procedure for sample preparation prior to high-performance liquid chromatography (HPLC). It is shown that the addition of ascorbic acid as antioxidant is necessary to prevent the generation of the researched analytes during this procedure. Nevertheless, the plant extracts do under certain conditions catalyze the oxidation of flavonoles resulting in benzofuranones.
authors.affiliation: School of Veterinary Medicine, Centre for Food Science, Department of Chemical Analytics, Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Jungbluth
authors.forename: Waldemar
authors.initials: W
authors.lastname: Ternes
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D001572:Benzofurans / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000032:analysis* / Q000378:metabolism; D044948:Flavonols; D006868:Hydrolysis; D019697:Onions / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D000975:Antioxidants; D001572:Benzofurans; D005419:Flavonoids; D044948:Flavonols; D001205:Ascorbic Acid