2.7.2. GCeMS analysis
The GCeMS analysis was performed on an Agilent 6890 gas chromatograph coupled with a 5975 mass spectrometer (Agilent Technologies, USA).
The carrier gas was helium with a flow rate of 1.1 mL/min. The separation was performed on a DB-WAX 30 m _ 0.25 mm _ 0.25 mm capillary column (Agilent Technologies,USA).
The initial oven temperature was 35 _C for 1 min, which was ramped to 100 _C at the rate of 8 _C/min and held for 3 min; subsequently, the temperature was ramped to 120 _C at the rate of 3 _C/min and held for 2 min; finally, the temperaturewas ramped to 230 _C at the rate of 5 _C/min and held for 5 min.
The mass detector was operated at 230 _C in an electron impact mode at 70 eV.
The ion-source temperature was 230 _C, while the transfer line temperature was 150 _C.
The chromatograms were recorded by monitoring the total ion currents in the 20e350 mass range.