963 (2002) 213–223 Journal of Chromatography A, www.elsevier.com / locate / chroma Determination of esters in dry and sweet white wines by headspace solid-phase microextraction and gas chromatography ´ ´ ´ J.J. Rodrıguez-Bencomo, J.E. Conde, M.A. Rodrıguez-Delgado, F. Garcıa-Montelongo, * ´ J.P. Perez-Trujillo Department of Analytical Chemistry, Nutrition and Food Science, University of La Laguna, 38071 La Laguna, Tenerife, Spain Abstract Headspace solid-phase microextraction (HS-SPME) was studied for the high-resolution gas chromatographic (HRGC) analysis of esters in wines. Five different SPME fibers were tested and the influence of different factors such as temperature and time of desorption, extraction time, extraction technique, stirring, sample and vial volume, sugar and ethanol content were studied and optimised using model solutions. The proposed HS-SPME–GC method is an appropriate technique for the quantitative analysis of esters in dry and sweet white wines.  2002 Elsevier Science B.V. All rights reserved. Keywords: Wine; Food analysis; Solid-phase microextraction; Headspace analysis; Esters 1. Introduction loss, artefact formation, use of environmentally hazardous solvents, difficulties in automation, etc. Wine quality is heavily influenced by flavour Solid-phase microextraction (SPME) is a relatively compounds. Up to several hundred compounds from novel technique introduced by Pawliszyn [2], which different chemical families in different concentra- combines direct extraction and pre-concentration tions account for wine flavour [1]. Such compounds without pre-treatment of samples. It is cheap, fast, come from grapes, fermentation processes and wine easily automated, no organic solvents are used and it ageing. However, both qualitatively and quantitative- avoids contact with samples as it works in headspace ly, fermentation compounds are the main group, when volatile compounds are analysed. especially esters, which play an important role in This technique has been used to characterise a white wine aroma. wide range of wine aroma compounds, including Classical analytical methods used for high-res- esters [3–9], or some particular family of compounds olution gas chromatographic (HRGC) analysis of such as monoterpenes [10–12], or sulphides and wine aroma compounds such as liquid–liquid ex- disulphides [13–16], or a particular compound like traction, static and dynamic headspace, molecular diacetyl [17], or methyl isothiocyanate [18], etc. distillation, solid-phase extraction, etc., have at least Most of these studies used manual SPME, while only one of the following disadvantages: taking a long a few used automatic SPME. time, laboriousness, possibility of contamination or The aim of this work was to apply the HRGC technique combined with automatic headspace (HS) SPME to develop a method to determine a set of *Corresponding author. Tel.: 134-922-318-036; fax: 134-922- esters (ethyl acetate, ethyl butyrate, ethyl hexanoate, 318-003. ´ E-mail address: jperez@ull.es (J.P. Perez-Trujillo). ethyl octanoate, ethyl decanoate, ethyl dodecanoate, 0021-9673 / 02 / $ – see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0021-9673(02)00551-4