2.2. Extraction of Essential Oils

Hydrodistillation (HD), using a Deryng system (the Polish version of the Clevenger apparatus), was used for isolating the essential oil in fresh herbs (dill, parsley, coriander, and mint). About 15.0 g of freshly chopped herbs shoots (aerial part of the plant, including stems and leaves) were put in a 500 mL round bottom flask, together with 1.0 g sodium chloride (NaCl), 150 mL of distilled water, and 50 µL of benzyl acetate as an internal standard (987 mg·L⁻¹). After the mixture started boiling, heating was maintained for 1 h. A cold refrigerant was used to condense the vapors, and 1 mL of cyclohexane was added to the Deryng apparatus at the beginning of the hydrodistillation process to retain the essential oil distilled from the samples of herbs shoots. After 60 min of extraction, the solvent, enriched with the volatile compounds, was transferred into a 2.5 mL vial, after drying it over anhydrous sodium sulfate (Na₂SO₄), and kept at −15 °C until the gas chromatography-mass spectrometry (GC-MS) analyses were conducted. The extractions were conducted in triplicate.