Optimization and validation of an automated DHS-TD-GC-MS method for the determination of aromatic esters in sweet wines.

A dynamic headspace sorptive extraction (DHS) combined with thermal desorption (TD) and coupled with gas chromatography-mass spectrometry (GC/MS) was developed for the determination of 11 esters which contribute to the fruity aroma in sweet wines. A full factorial (4 factors, 2 level) experiment design was used to optimize the extraction conditions and the results were evaluated by multiple linear regression (MLR) and principal component analysis (PCA). The esters showed optimal extraction using an extraction temperature of 30°C during 20 min, and a subsequent purge volume of 300 mL and dry volume of 50 mL. Afterwards, quantification was achieved using calibration curves constructed for each ester with linear regression equations having correlation coefficients (R(2)) ranging from 0.9894 to 0.9981. The proposed method was successfully validated and showed good intermediate precision, repeatability and accuracy values for all the monitored compounds. Finally, the method was applied to quantify esters, with fruity aromatic notes, of sweet white and red wines, elaborated with different winemaking processes.