2.8. Pyrolysis gas chromatography-mass spectrometry (Py-GC/MS)
Py-GC/MS analysis were carried out using an EGA/PY-3030D multi-shot pyrolyzer (Frontier Laboratories Ltd., JPN) coupled to a Trace GC Ultra gas chromatograph equipped with a TSQ Quantum XLS mass spectrometer (AGILENT Inc, USA). The sample (about
1.0 mg) was preheated at 300 C for 3 min and pyrolyzed at 450 C for 1 min under a helium (He) atmosphere. The volatiles were carried by carrier gas He through a HP-5MS capillary column (30.0 m, i.d. 0.32 mm 1.0 mm stationary phase thickness) and the mixture was separated. The GC oven temperature program was as follows: 70 C (held for 2 min) to 230 C at 20 C/min (held for
16 min). The interface temperature of GC to MS was 250 C. Electron ionization (70 eV) was used to ionize the pyrolysis products. The MS source temperature was 230 C.