Molecules | Free Full-Text | Optimization of Headspace Solid Apr 08, 2022 · Then, the homogenate was weighed (0.5–3.5 g) into the 15 mL screw cap headspace vial fitted with the PTFE/silicone septa containing 2 mL of ultrapure water, a certain amount of Na 2 SO 4 (0–1.25 g), 4 μL of difurfuryl sulfide (21.4 mg/L), and a magnetic stirring rotor, and then the headspace vial fitted with the