title: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of polygalloyl polyflavan-3-ols in grape seed extract.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to characterize the polygalloyl polyflavan-3-ols (PGPF) in grape seed extracts. Masses corresponding to a series of PGPF units inclusive of nonamers were observed in the positive-ion reflectron mode. Masses of PGPF inclusive of undecamers were observed in the positive-ion linear mode, providing the first known evidence of PGPF of this size. Soluble PGPF of grape seed extracts were precipitated by complexation with Yb(3+). The PGPF were then recovered by dissolving the precipitate in water and removing the Yb(3+) by a weakly acidic cation-exchange resin (Amberlite IRP-64). Comparisons of HPLC chromatograms of the crude grape seed extract prior to precipitation with Yb(3+) and after recovery of the PGPF indicated that 96% of the phenolic compounds were precipitated and 99% of the precipitated PGPF were recovered by cation-exchange resin. These results indicate that MALDI-TOF MS is able to determine the mass distribution of complex mixtures of oligomeric PGPF and that precipitation of PGPF by Yb(3+) is useful for isolation and quantification.
authors.affiliation: Departments of Animal Sciences, Chemistry, and Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: C G
authors.initials: CG
authors.lastname: Krueger
authors.forename: N C
authors.initials: NC
authors.lastname: Dopke
authors.forename: P M
authors.initials: PM
authors.lastname: Treichel
authors.forename: J
authors.initials: J
authors.lastname: Folts
authors.forename: J D
authors.initials: JD
authors.lastname: Reed
mesh_terms: D005419:Flavonoids / Q000032:analysis*; D044948:Flavonols; D010936:Plant Extracts / Q000737:chemistry; D019685:Rosales / Q000737:chemistry* / Q000196:embryology; D012639:Seeds / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D005419:Flavonoids; D044948:Flavonols; D010936:Plant Extracts