Journal of Chromatography A, 995 (2003) 11–20 www.elsevier.com / locate / chroma Optimisation of headspace solid-phase microextraction for the analysis of volatile phenols in wine a * ] ´ ´ ´ ´ Remedios Castro Mejıas , Ramon Natera Marın, M de Valme Garcıa Moreno, ´ Carmelo Garcıa Barroso ´ Analytical Chemistry Department, Faculty of Sciences, University of Cadiz, P .O. Box 40, E-11510, Pol. Rio San Pedro, ´ Puerto Real, Cadiz, Spain Received 1 October 2002; received in revised form 12 March 2003; accepted 25 March 2003 Abstract Headspace solid-phase microextraction has been applied to the analysis of volatile phenols in wine. Silica fibre coated with Carbowax–divinylbenzene was found to be more efficient at extracting these compounds than other fibres such as those coated with polydimethylsiloxane, polyacrylate, carboxen–polydimethylsiloxane, and polydimethylsiloxane–divinylbenzene. Different parameters such as extraction time, temperature of the sample during the extraction, ionic strength and sample volume were optimised using a two-level factorial design expanded further to a central composite design, in order to evaluate several possibly influential and / or interacting factors. The headspace (HS)-SPME procedure developed shows adequate detection and quantitation limits, and linear ranges for correctly analysing these compounds in wine. The recoveries obtained were close to 100%, with repeatability values lower than 16%. The method was applied to a variety of white and red wines.  2003 Elsevier Science B.V. All rights reserved. Keywords: Wine; Headspace solid-phase microextraction; Phenols 1. Introduction (4-ethylphenol and 4-ethylguaiacol) are responsible for animal and smoky odours [2], while vinylphenols Volatile phenols represent a large family of sub- (4-vinylphenol and 4-vinylguaiacol) can be respon- stances, some of which possess a strong odorous sible for heavy pharmaceutical odours [3]. Vin- activity which can influence the aroma of numerous ylphenols are produced by yeasts of the genus fermented beverages. These compounds are consid- Brettanomyces / Dekkera, through decarboxylation of ered part of the aroma composition of wines. These trans ferulic and trans p-coumaric acids. Later, are principally vinylphenols in white wines and vinylphenols are transformed by reduction reactions ethylphenols in red wines [1]. Some of these com- into ethylphenols [4,5]. So, it is important for pounds can produce unpleasant odours, affecting winemakers to control the concentrations of these negatively the quality of the wine. Ethylphenols compounds in their wines. The analysis of volatile phenols is carried out by gas chromatography after a previous extraction and *Corresponding author. Tel.: 134-956-016-363; fax: 134-956- concentration stage. De Santis et al. [6] determined 016-460. ´ E-mail address: remedios.castro@uca.es (R. Castro Mejıas). the volatile phenols of ‘‘Aleatico di Gradoli Riserva’’ 0021-9673 / 03 / $ – see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016 / S0021-9673(03)00541-7