The headspace vials used in this study were 75.5 × 22.5 mm, 20 mL, screw neck, clear glass vials (Gerstel Inc., Linthicum, MD, USA, product number #093640-036-00) with magnetic screw caps with blue silicone/PTFE septa (Gerstel Inc., Linthicum, MD, USA, product number #093640-040-00).