# Volatile Composition of Fortification Grape Spirit and Port Wine: Where Do We Stand?
## 4 Methodologies for the Characterization of Grape Spirits and Port Wines' Volatile Components  
Apart from the sampling and data processing and interpretation, the selection and optimization of the extraction methodology and the instrumental analysis are two fundamental steps in the construction of an analysis workflow, to provide high-quality data that may be useful to disclose information related to grape sprit and Port wine volatile composition and aroma characteristics, among others. The volatile profiles of the fortification grape spirits and Port wines have been studied using different extraction methodologies combined with chromatographic techniques, especially gas chromatography, as listed in Table 1. For each matrix, the references are listed in chronological order to assess trends over time in the techniques used. As far as our research allowed, only four publications were identified for the determination of grape spirit volatile components [3; 29; 45; 46], and 24 publications were reported for Port wine [3; 6; 8; 9; 11; 12; 13; 14; 15; 16; 17; 21; 23; 24; 26; 27; 21; 23; 24; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53]. For untargeted analysis, liquid-liquid extraction (LLE) combined with gas chromatography coupled with mass spectrometry (GC-MS) has been mainly used for both matrices; however, in the last two decades, solid phase microextraction (SPME), a solvent-free technique, emerged as a suitable extraction approach to study these matrices. The targeted analyses, such as for carbonyl compound determination, were performed using derivatization followed by GC-MS [15; 27; 29; 45], reverse-phase high-performance liquid chromatography coupled to a diode array detector (RP-HPLC-DAD) [46] and HPLC [16]. Sotolon detection is another example of target analysis performed on these matrices, and it was also determined using GC-MS [14] and RP-HPLC-DAD [51]. LLE is a solvent extraction technique that has been commonly used for achieving exhaustive enrichment with the purpose of extracting volatile components from beverages, according to their partition coefficients between solvent and beverage. The procedure is laborious and, in addition to extraction, it also requires the concentration of the solutes by evaporation of the solvent. This stage can result in the loss of more volatile analytes, along with possible interferences derived from solvent impurities in the following chromatographic analysis. If the solvent evaporation is performed under vacuum and using a trap with liquid nitrogen, for more efficient condensation, it is possible to decrease the evaporation temperature, preventing and/or reducing the degradation of analytes or formation of artefacts [54]. Due to its intermediate polarity (dielectric constant \(\varepsilon\) = 9.1) and high volatility, dichloromethane has been widely used for the extraction of volatile compounds in these matrices (Table 1) [54; 55]. However, as observed for other halogenated solvents, it represents some concerns for users and for the environment (carcinogenic, mutagenic, or toxic to reproduction substance--CMR) and, therefore, its use should be restricted and handled cautiously [55].