Analysis of Low-Molecular-Weight Phenols and Polyphenols

A method of sample preparation for analysis of grape flavonols is 

A method of wine sample preparation is to perform liquid-liquid extraction of 50 mL of wine previously concentrated to 15 mL under vacuum at 30 °C to eliminate ethanol. Two extractions with diethyl ether (3x5 mL) and ethyl acetate (3 x 15 mL) are performed. The organic phases are combined, dried with anhydrous Na2S04, the solvent is then removed under vacuum finally, the residue is dissolved in 2mL of methanol/H20 (1 1) and filtrated 0.45 pan (Monagas et al., 2005). In this analysis, several classes of nonanthocyanic phenols are detected flavan-3-ols and flavonols, hydroxycinnamoyltartaric acids, resveratrol 

---