Thermal desorption from the SPME fibre was carried out at
250 C in the injection port of the GC set in splitless mode. During
desorption the oven was held at 40 C for 3 min then the solid CO2
beaker removed immediately and the GC run started. After 0.5 min
the split was opened and the oven was held at 40 C for a further
2 min, before it was raised to 280 C at a rate of 4 C/min. The carrier
gas was helium at a flow rate of 1 mL/min. The mass spectrometer
was operated in electron impact mode at an ionisation voltage
of 70 eV and ion source temperature of 170 C. A series of n-alkanes
(C6–C25) were analysed under the same conditions to obtain linear
retention index (LRI) values for the volatile components