Determination of volatile phenols in red wines by dispersive liquid-liquid microextraction and gas chromatography-mass spectrometry detection.

A new method was developed for analysing 4-ethylguaiacol and 4-ethylphenol in the aroma of red wines using dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry detection (GC-MS). Parameters such as extraction solvent, sample volume and disperser solvent were studied and optimised to obtain the best extraction results with the minimum interference from other substances, thus giving clean chromatograms. The response linearity was studied in the usual concentration ranges of analytes in wines (50-1500 microg/L). Repeatability and reproducibility of this method were lower than 5% for both volatile phenols. Limits of detection and limits of quantification were also determined, and the values found were 28 and 95 microg/L for 4-ethylguaiacol and 44 and 147 microg/L for 4-ethylphenol, respectively. This new method has been used for the determination of the volatile phenols concentration in different samples of Tannat wine affected by Brettanomyces contamination.