2.2. Instruments
TheGC–MS instrumentused toseparate anddetectbacterialVOCs
wasaTraceGCUltrafittedwithaPolarisQ ion trapmassspectrometer
with Xcaliber 1.4 SR1 software. Separation of VOCs was carried out
using a 30m 0.25 mm ID 0.25mm VF-waxMS capillary column.
The S/SL injector was set at 230 C and operated in split mode with a
flow rate of 10 mlmin1 and a split ratio of 10. The temperature
program used was: 50 C held for 2 min then increased at a rate of
10–220 C min1 with a final 2 min hold. The carrier gas was helium
with a flow rate of 1.0ml min1
. Electron ionisation (EI) was used
(70 eV), and the mass spectrometer was operated in total scan mode
overanm/z range of50–650 amu. Thetransferlinewas heldat 250 C
while the ion source temperature was maintained at 260 C.