Quantification of three galloylglucoside flavour precursors by liquid chromatography tandem mass spectrometry in brandies aged in oak wood barrels

• The first LC–MS/MS method was developed for the quantification of the galloyl glucoside precursors of vanillin, 3,4,5-trimethoxyphenyl and 3-oxo-α-ionol.
• The method was completely validated.
• Vanillin-β-d-xylopyranoside was synthesised for the first time to be used as internal standard.
• Analyzed the galloyl glucoside precursors were found in Brandy samples in hundred of micrograms per liter.

Vanillin-(6′-O-galloyl)-β-glucopyranoside (VGG), 3,4,5-trimethoxyphenyl-(6′-O-galloyl)-β-glucopyranoside (TMPGG), and (6R,9R)-3-oxo-α-ionol-9-O-(6′-O-galloyl)-β-glucopyranoside (macarangioside E) were identified as aroma precursors in oak wood.An LC–MS/MS method was developed and validated to quantify these three galloylglucoside compounds in brandies aged in oak barrels. The detection system consisted of a triple quadrupole mass analyser operating in multiple reaction monitoring (MRM) mode. For the first time, vanillin-β-d-xylopyranoside (VX) was synthesised for use as an internal standard. The detection limits (48 μg L−1 for VGG, 52 μg L−1 for TMPGG, and 19 μg L−1 for macarangioside E) were low enough to quantify these aroma precursors in spirits without any sample preparation.