Optimization of solid phase microextraction analysis of aroma compounds in a Portuguese muscatel wine must

The fundamental suitability of solid-phase microextraction (SPME) has been investigated for the quantitative determination of eight aroma compounds present in a Portuguese muscatel wine must. The method has been optimized using a commercially available fiber coated with 85 μm polyacrylate (PA). The matrix effect was evaluated by comparing the results obtained with the standard additions method to those obtained, for the same analyte, by means of a calibration curve (internal standard method). The results obtained with the standard additions method show poor accuracy and higher confidence limits than those obtained by the calibration curve. Experiments during the SPME process were carried out to investigate the influence of (1) ethanol concentration and (2) high concentrations of one analyte on the absorption of minor components. No significant decrease in peak response was observed either for ethanol concentration from 3 to 12% or for excess concentration of one analyte over the others. The method was evaluated with respect to the linearity, within run precision and limit of detection. The curves obtained by plotting mass ratio vs. area ratio showed higher correlation coefficient R²>0.99 for most compounds. The use of internal standard minimizes quantitative errors due to the extraction process and injection. Ethanol concentration does not seem to affect quantitative determination. Polydimethylsiloxane (PDMS) fiber is more suitable for the analysis of esters, whereas polyacrylate is suitable for alcohols of low molecular weight and terpene quantification. The method has been applied to a Portuguese wine must to investigate the recovery of its aroma profile, formed by Saccharomyces cerevisiae during the wine-must fermentation, using organophilic pervaporation [1]. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 236–242, 2001