0.25 µm film thickness (Thermo Fisher Scientific, Bellefonte, PA USA) 9.2 SPME fiber – 57341-U coated with PDMS, d f 100 µm Supelco Bellefonte, PA USA 9.3 Headspace vials – 20 mL flat 3205551 bottom, clear glass, beveled edge 9.4 PTFE – faced butyl rubber septa 3205532 for headspace vials – 20 mm, septa Butyl/PTFE