To optimize the GC conditions, several injection temperatures and temperature programs were tested. The best results were obtained using the following program: the column temperature was initially maintained at 40 C for 1 min after injection, increased at 3 C/min–120 C, then programmed at 15 C/min–250 C and kept for 15 min.
Injections were done using the splitless system. Helium at 1.0 mL/min was used as carrier gas. Injector was main-tained at 250 C, the transfer line temperature was 250 C and the ion source temperature was kept at 230 C. The ionization occurred with a kinetic energy of the impacting electrons of 70 eV. Mass spectra and reconstructed