Use Agilent6890N Gas Chromatograph; use high pure helium for carrier gas; FID detector; HP-5 (30
m × 0.32 mm × 0.25 μm) chromatographic column; column temperature is from 70 ℃ (to keep 2 min)
to 220 ℃ with 15 ℃/min rate, with 2 ℃/min rate rose to 270 ℃, with 5 ℃/min rate rose to 290 ℃ (to
keep 3 min ); the carrier gas is nitrogen.