. Wine samples
Red wines used in this study were from Bordeaux (vintages from 1974 to 2015), produced by standard winemaking procedures with or without wood contact. They were analyzed in 2006 and in 2015.
2.3. Wine extraction
2.3.1. Procedure 1 (identification procedure)
Red wine (0.5 L) was extracted with pentane/dichloromethane (1/1, v/v; 3 × 160 mL) dried over Na2SO4 and concentrated to 50 mL by gentle evaporation of the solvent with a Rotavapor system. The organic phase was treated three times with an aqueous Trizma buffer (0.1 M; pH 10, 50 mL). Then, the organic extract containing neutral and basic compounds was dried over Na2SO4 and concentrated to 1 mL under nitrogen flow.
2.3.2. Procedure 2 (assay procedure)
Red wines (100 mL) were spiked with 100 μL 3-octanol (100 mg/L, EtOH) and extracted three times with pentane/dichloromethane (1/1, v/v; 3 × 10 mL). The organic layer was dried over Na2SO4 and then concentrated to 0.5 mL under nitrogen flow (100 mL/min).
2.4. Partial purification of crude red wine extract on silica gel chromatography