title: Determination of quercetin in human plasma using reversed-phase high-performance liquid chromatography.
abstract: A method is reported for the measurement of quercetin in human plasma using reversed-phase high-performance liquid chromatography (HPLC). Quercetin and kaempferol (as internal standard) were spiked into plasma samples and extracted using C18 Sep-Pak Light cartridges (efficiency > 85%). Flavonoids were eluted with aqueous acetone (50% v/v, pH 3.5), dried down and redissolved in aqueous acetone (45% v/v, pH 3.5). The increased osmolarity promoted a phase separation and the water-saturated acetone layer, containing the flavonoids, was analysed by HPLC with aqueous acetone mobile phase (45% v/v acetone in 250 mM sodium dihydrogen sulphate. The mixture was adjusted to pH 3.5 with phosphoric acid and used at a flow-rate of 1.0 ml/min) and mu Bondapak C18 column (150 x 3.9 mm I.D., 10 microns particle size). The detection limit (A375 nm) for quercetin in plasma was 0.1 microgram/ml (300 nM). The method also detects metabolites of quercetin, although these are not yet identified.
authors.affiliation: CRC Institute for Cancer Studies, University of Birmingham School of Medicine, Edgbaston, UK.
authors.forename: B
authors.initials: B
authors.lastname: Liu
authors.forename: D
authors.initials: D
authors.lastname: Anderson
authors.forename: D R
authors.initials: DR
authors.lastname: Ferry
authors.forename: L W
authors.initials: LW
authors.lastname: Seymour
authors.forename: P G
authors.initials: PG
authors.lastname: de Takats
authors.forename: D J
authors.initials: DJ
authors.lastname: Kerr
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D011794:Quercetin / Q000097:blood*; D012015:Reference Standards; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence
chemical_list: D011794:Quercetin