Analytica Chimica Acta 563 (2006) 84–92 Analysis of phenolic compounds in Muscatel wines produced in Portugal M.N. Bravo a,b , S. Silva b,c , A.V. Coelho b,e , L. Vilas Boas b,d , M.R. Bronze a,b,c,∗ a Faculdade de Farm´ acia de Lisboa, Av. das For¸ cas Armadas, 1649-019 Lisboa, Portugal b Instituto de Tecnologia Qu´ ımica e Biol ´ ogica, Apartado 127, 2784-505 Oeiras, Portugal c Instituto Biologia Experimental e Tecnol´ ogica, Apartado 12, 2781-901 Oeiras, Portugal d Instituto Superior T´ ecnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal e Universidade de ´ Evora, Departamento de Qu´ ımica, 7000 ´ Evora, Portugal Received 19 August 2005; received in revised form 14 November 2005; accepted 21 November 2005 Available online 6 January 2006 Abstract A liquid chromatography method associated with mass spectrometry and diode array, fluorescence and electrochemical detectors was used in order to study phenolic composition of Muscatel sweet wines from Set ´ ubal region in Portugal. Samples were collected during winemaking production at different representative producers of this region. Total phenolic contents of samples were also determined using the Folin–Ciocalteu method. Mass spectrometry results show that atmospheric pressure chemical ionisation (APCI) in negative mode presents higher sensitivity for the majority of the compounds studied. Some phenolic acids, stilbenes as resveratrol and piceid, and flavonols as quercetin and quercetin glycosides were identified in these Muscatel wines. For resveratrol, piceid, gallic acid, protocatechuic acid, catechin and quercetin, fluorescence and electrochemical properties were used as complementary or alternative methods of detection. Differences in phenolic composition and total phenolic contents were found among samples collected. © 2005 Elsevier B.V. All rights reserved. Keywords: Muscatel wine; Phenolic compounds; Fluorescence detector; Electrochemical detector; Mass spectrometry; Folin–Ciocalteu 1. Introduction Phenolic compounds play an important role in colour and flavour of foods and beverages and its regular consumption on a diet has been associated with beneficial effects for human health [1]. Some phenolic compounds found in wines are antioxidants contributing to a reduction in the risk of cardiovascular diseases, others such as resveratrol, gallic acid and quercetin have been claimed to have activity against allergies, inflammation, hyper- tension, arthritis and carcinogens [2–6]. White wines, with a lower phenolic content than red wines, have lower antioxidant activity, although some phenolic compounds present in these wines are more effective in the in vitro inhibition of LDL oxi- dation process [7]. The type and concentration of phenolic compounds in wines is influenced by the chemical composition of the raw materi- als (grapes) which are influenced by the variety, ripening stage, atmospheric conditions during ripening and type of soil. The ∗ Corresponding author. Tel.: +351 214469770; fax: +351 214417062. E-mail address: mbronze@itqb.unl.pt (M.R. Bronze). techniques used during the winemaking process of the wine and ageing conditions [8–10] are also important. Phenolic aldehy- des (e.g. vanillin), benzoic acids (e.g. gallic acid), hydroxycin- namic acids (e.g. caffeic, ferulic and p-coumaric acids) and their esters obtained by condensation with tartaric acid (hydroxycin- namoyltartaric acids), flavanols, flavonols (e.g. quercetin) and anthocyanins are extracted from grapes during the winemak- ing process. Also flavan-3-ols as catechins present in the grape as monomers or polymerized to form proanthocyanidins and hydrolysable tannins [11,12] and stilbenes, as resveratrol or its glycoside form (piceid) occur in wine [13,14]. Some phenolic compounds can be extracted from wood dur- ing the ageing stage and oxidation reactions may also occur increasing the stability of the wine and its pleasant sensorial characteristics. Phenolic compounds have been analysed by liquid chro- matography (LC) with diode array (DAD), fluorescence (FD) [10,14,15] and electrochemical (ED) detection [16,17]. Liq- uid chromatography with mass spectrometry (MS) using atmo- spheric pressure ionisation (electrospray or chemical ionisation) has also been used [18] in order to identify their chemical structures. 0003-2670/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2005.11.054