Spme fibre 57326u

Seven hornets (4 queens and 3 workers) were kept one by one the same day of their capture in a pyramidal acrylic box (Figure 3a). The structure of this pyramid is useful to introduce the hornets to a glass vial. The pyramid was also darkened, except for its vertex, by placing a black cloth on it. Thereby, the hornets tended to exit the pyramid through the vertex. Each hornet was then transferred to a glass vial with aluminium foil placed on both sides of the container to limit air movement (Figure 3b). A 65 µm thick polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre (Supelco SPME fibre 57326U, Darmstadt, Germany) was fixed at the glass bottle, with the hollow SPME needle stuck through the aluminium foil, exposing the fibre, close to the hornet, to adsorb the volatile compounds present in the headspace. Before use, the SPME fibre was preconditioned and thermally cleaned. This was done thermally by exposing the fibre at a conditioning temperature of 250 °C for 30 min in the GC injection port. The chosen extraction mode was Headspace (HS) since the analytes of interest are highly volatile. Thus, the fibre was introduced into the glass vial with the hornet and exposed in dark for 30 min at 25 °C. After this period, the fibre was retracted and transferred to the gas phase chromatograph (GC) injector where the compounds were desorbed for 5 min.