A new analytical method for the determination of six volatile short and medium-chain fatty acids (acetic, propionic, isobutyric, isovaleric, hexanoic, and octanoic acids) through liquid–liquid extraction with diethyl ether, followed by GC-FID analysis, was developed and validated. The extraction conditions were optimized by evaluating the effect of the number of extractions (1 to 3) and the effect of the addition of salts (NaH₂PO₄, (NH₄)₂SO₄, NaCl, (NH₄)₂SO₄/NaH₂PO₄) to increase the concentration of the analytes in the ethyl ether phase. Results showed that a single extraction allows obtaining the highest sensitivity (due to the impossibility of evaporating the solvent to avoid losses of the analytes). The use of salting out agents, in particular, NaH₂PO₄, showed an important increase in the extraction extent, on average, 1.5 times higher as compared to the extraction performed without salt. The proposed method is rapid, requiring a total of 30 min for preparation and analysis, and it makes use of small amounts of sample (500 µL) and solvent (400 µL). The method was then applied to quantify the analytes in 5 white wines and 5 red wines, allowing to highlight some clear differences between red and white wines, with the red ones having a significantly higher amount of acetic acid (715.7 ± 142.3 mg/L in red wines and 351.5 ± 21.2 mg/L in white wines) and the white wines having a significantly higher amount of hexanoic and octanoic acid (6.1 ± 3.0 mg/L and 2.6 ± 0.8 mg/L, respectively, are the mean concentrations in white wines, and 4.7 ± 0.8 and 2.4 ± 0.4 mg/L, respectively, are the mean concentrations in red wines).

Eugenol and linalool are often the most abundant volatile compounds found in basil (Ocimum basilicum L., Lamiaceae) leaves, and they are interesting for the aroma they provide and for their numerous beneficial bioactivities. Their determination is thus needed for several purposes. In the present study, to avoid the previous isolation of essential oil, the direct solvent extraction is proposed coupled with a transmethylation to convert acyl lipids into fatty acids methyl esters (FAMEs), thus assessing the possible simultaneous analysis of eugenol and linalool with FAMEs by gas chromatography coupled to flame ionization detector (GC-FID). The method has been validated and applied to ten basil leaves samples in which eugenol and linalool were found in mean concentrations of 2.80 ± 0.15 and 1.01 ± 0.04 g kg⁻¹ (dry weight), respectively. FAMEs composition was dominated by linolenic acid (52.1–56.1%) followed by palmitic acid (19.3–22.4%) and linoleic acid (9.6–11.3%). The ratio of n6-polyunsaturated fatty acids (PUFAs)/n3-PUFAs was in the range of 0.17–0.20 in the investigated samples. The proposed method exploits a rapid procedure requiring 40 min, making use of a small amount of solvent and allowing the simultaneous determination of molecules contributing to assess the quality of this worldwide appreciated herb.