Extraction of volatile compounds using SDE technique

Every 30.0 g homogenized sample was mixed with 1,000 mL of distilled water and the pH was adjusted at 7.0 by dilute NaOH/HCl solution. For the quantitative analysis of volatile organic compounds, 100 ppm, 10 mL n-butyl benzene was added as an internal standard. Volatile organic compounds were extracted from both leaves by modified simultaneous distillation extraction (SDE, Likens & Nickerson types) apparatus with 100 mL redistilled n-pentane:diethyl ether (1:1, v/v) mixture. The experiment was maintained under normal atmospheric pressure for 3 h (Schultz et al., 1977). The SDE extract was dehydrated overnight by adding 10 g of anhydrous Na₂SO₄. Finally, the vigreux column was used to concentrate the extract volume to 1.5 mL. After that, it was again concentrated to 0.5 mL under N₂ gas mild flush. Finally, the concentrated extract was injected into the GC/MS system for determination of volatile organic compounds (Khan et al., 2015).