An Agilent 6890N series gas chromatograph equipped with an Agilent MSD 5973N mass spectrometer (MS) detector and a DB-Wax capillary column (30 m ×0.25 mm, 0.25 μm film thick) was used. The temperature was programmed from 40 to
240°C (3°C/min until 160°C and 10°C/min until 240°C). Helium was used as a carrier gas at 1 ml/min constant flow rate and a scan range of 40 to 250 Daltons with the MS was operated at 70 eV with ion source temperature of 230°C.