title: Toward unraveling grape tannin composition: application of online hydrophilic interaction chromatography × reversed-phase liquid chromatography-time-of-flight mass spectrometry for grape seed analysis.
abstract: Despite the significant importance of tannins in viticulture and enology, relatively little is known about the detailed chemical composition of these molecules. This is due to challenges associated with the accurate analytical determination of the highly structurally diverse proanthocyanidins which comprise tannins. In this contribution, we address this limitation by demonstrating how online comprehensive two-dimensional liquid chromatography (LC × LC) coupled to high resolution mass spectrometry (HR-MS) can be exploited as a powerful analytical approach for the detailed characterization of grape seed tannins. Hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RP-LC) were employed in the two dimensions to provide complementary information in terms of separation according to hydrophilicity and hydrophobicity, respectively. Online coupling of HILIC × RP-LC with fluorescence detection and electrospray ionization MS delivered high resolution analysis in a practical analysis time, while allowing selective detection and facilitating compound identification. Time-of-flight (TOF) MS provided high acquisition rates and sensitivity coupled to accurate mass information, which allowed detection of procyanidins up to a degree of polymerization (DP) of 16 and a degree of galloylation up to 8 in a red grape seed extract. This analytical methodology promises to shed new light on these important grape constituents and potentially on their evolution during wine production.
authors: Stellenbosch University , Department of Chemistry and Polymer Science, Private Bag X1, Matieland, Stellenbosch, Western Cape 7602, South Africa.
authors: Kathithileni M
authors: KM
authors: Kalili
authors: Jochen
authors: J
authors: Vestner
authors: Maria A
authors: MA
authors: Stander
authors: André
authors: A
authors: de Villiers
mesh_terms: D002853:Chromatography, Liquid; D056604:Grape Seed Extract / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D013058:Mass Spectrometry; D009862:Online Systems; D013634:Tannins / Q000032:analysis* / Q000737:chemistry*; D013997:Time Factors; D027843:Vitis / Q000737:chemistry*
chemical_list: D056604:Grape Seed Extract; D013634:Tannins