The modulator (i) accumulates and traps, (ii) refocuses and (iii) rapidly releases the adjacent fractions of the first Veliparib datasheet dimension column effluent (Semard, Gouin, Bourdet, Bord, & Livadaris, 2011). GC × GC is an established technique, offering superior separation capabilities afforded by high peak capacity, selectivity, structural

chromatographic peak organisation, and sensitivity enhancement compared to 1D-GC. Considerably more information about constituents of complex samples may be provided, while the time of the analysis remains the same as in 1D-GC (Marriott & Shellie, 2002). The application of GC × GC to wine volatiles and other beverages has recently been reviewed (Welke & Zini, 2011) and examples of investigations of wine Dinaciclib supplier compounds may be cited. These include determination of methoxypyrazines in Sauvignon Blanc wines (Ryan, Watkins, Smith, Allen, & Marriott, 2005); methoxypyrazines in Cabernet Franc berries and the resulting wines (Ryona, Pan, & Sacks, 2009); furans, lactones, volatile phenols, and acetals in Madeira wines (Perestrelo, Barros,

Camara, & Rocha, 2011); volatiles in Cabernet Sauvignon wine (Robinson, Boss, Heymann, Solomon, & Trengove, 2011b), Pinotage wines (Weldegergis et al., 2011) and Fernão-Pires grapes (Rocha et al., 2007). Former work of this research group on Merlot volatiles has been recently published, where the advantages of GC × GC/TOFMS have been highlighted, through a detailed characterisation of Merlot volatiles and also with a preliminary approach of the use of multivariate analysis for discrimination of 24 wine samples according to grape variety (Welke, Manfroi, Zanus, Lazarotto, & Zini, 2012a). The main purpose of this study is to determine which components may be potential markers of grape variety of different wines made of Cabernet Sauvignon, Merlot, Chardonnay, Sauvignon Blanc

and 50% Chardonnay/50% Pinot Noir grape varieties, using HS-SPME-GC × GC/TOFMS and chemometric analysis. The analysis of possible coelutions of volatile compounds in the first chromatographic dimension and the separation of formerly coeluted compounds by GC × GC MTMR9 are also discussed. All wines investigated (∼13% ethanol, v/v) were of 2009 vintage and were produced in Serra Gaúcha region (latitude 29°S, longitude 51°W, altitude 600–800 m). These samples were provided by Empresa Brasileira de Pesquisa Agropecuária Uva e Vinho (EMBRAPA) in sealed 750-mL bottles and were chosen as the best wine samples in the “National Evaluation of Wines of 2010” event promoted by the Brazilian Association of Enology. Fifty-four samples produced from grapes of Vitis vinífera cultivars were analysed. Each one of them was from different production batches.