Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of polygalloyl polyflavan-3-ols in grape seed extract.

C G Krueger, N C Dopke, P M Treichel, J Folts, J D Reed

Departments of Animal Sciences, Chemistry, and Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.

Journal of agricultural and food chemistry 2000 May

filter terms:

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.

Citation

C G Krueger, N C Dopke, P M Treichel, J Folts, J D Reed. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of polygalloyl polyflavan-3-ols in grape seed extract. Journal of agricultural and food chemistry. 2000 May;48(5):1663-7