| Abstract: | Headspace solid phase microextraction (HS-SPME) was investigated as a solvent-free alternative method for the extraction and determination of 4-ethylphenol (EP) and 4-ethylguaiacol (EG) in red wine by capillary gas chromatography with flame ionization detection (FID) and compared to liquid-liquid extraction.For HS-SPME, better results were obtained with saturated sodium chloride samples, at 55 °C, using a 85 μm polyacrylate fiber. An absorption time of 40 min was needed to reach the absorption equilibrium for EG. This 40-min duration corresponds to the beginning of EP equilibrium and was selected for the experiments. In these conditions, the calibration graphs were linear in the range 5-5000 μg l−1 and the sensitivity was nearly the same for the two compounds. The detection limits were in the low μg l−1 range. In model wine solutions, result obtained with the liquid-liquid extraction method exhibit a linear calibration between 25 and 10,000 μg l−1 with a detection limit of 1 μg l−1, but, the relative standard deviations of the EP and EG result in the low concentration range (<50 μg l−1) are higher than those obtained by HS-SPME (15% compared to 2% for EP and 12% compared to 5% for EG). Taking into account the numerous volatile compounds in wine, HS-SPME is a rapid and valid alternative technique for use in the determination of ethylphenols at trace levels. |
