Advances in the Dereplication of Aroma Precursors from Grape Juice by Pretreatment with Lead Acetate and Combined HILIC- and RP-HPLC Methods

Glycosidic aroma precursors (GAPs) contribute to the varietal flavor of wine. Researchers have applied various sample preparation and analytical methods in attempts to achieve their separation and identification. However, mass spectrometric methods still fail to unequivocally define their structures. We have previously reported the separation of GAPs in their natural form and elucidated their structures by nuclear magnetic resonance (NMR) spectroscopy. In this study, we confirm the effectiveness of our established procedure and present methodological improvements. Grape juice was treated with lead (II) acetate and repeatedly chromatographed to give seven pure GAPs. Their chemical structures were characterized by MS(n) fragmentations and 1D- and 2D-NMR spectra. Ten GAPs were analyzed by both hydrophilic interaction liquid chromatography (HILIC) and reversed phase high performance liquid chromatography (RP-HPLC) to compare the two chromatograms. A selection of known phenols was treated with lead (II) acetate in order to check its binding properties.