3.8. Headspace Solid-Phase Microextraction

Volatile compounds of B. heterophylla were extracted using the HS-SPME technique; the extraction procedure was conducted as follows: 50 mg of aerial parts, 2 g of sodium chloride, and 15 mL of water (HPLC grade) were mixed in a hermetically sealed vial. Each fiber (CAR/PDMS, DVB/CAR/PDMS, PDMS/DVB and PDMS) was introduced into the vial and exposed to the headspace of the sample for 15 min, at room temperature, keeping the sample magnetically stirred. After sampling, the SPME fibers were directly inserted into the GC injector port and the fibers thermally desorbed. A desorption time of 2 min at 250 °C was used. Before GC–MS analysis, the fibers were conditioned in the injector of the GC system, according to the instructions provided by the manufacturer. All samples were analyzed in triplicate and the relative proportions of individual components adsorbed to the fibers under these conditions was calculated based on the total ion chromatogram (TIC) peak areas as a percentage of the sum of all peak areas. The GC-MS conditions were described in Section 3.7. The SPME fibers used in this study were purchased from Supelco Inc. (Bellefonte, PA, USA).