Sample preparation ethyl phenols

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... 

Aspects of sample preparation have been reviewed. Phenols and aromatic amines, although amenable to EC oxidation detection, tend to be relatively water soluble and thus polar extraction solvents such as ethyl acetate may have to be used if liquid-liquid extraction (LLE) is to be employed. Solid-phase extraction (SPE), using disposable cartridges or plastic syringe barrels packed usually with chemically-modified silica materials (Table 4.2) analogous to those used in HPLC columns, but with greater porosity, provides an alternative and may be more effective in extracting relatively hydrophilic analytes. On-line sample preparation procedures such as prior to EC detection have also been described. 

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