Electron Impact ionization experiments were performed on a Finnigan TSQ700 triple quadrupole mass spectrometer Finnigan MAT, San Jose, CA) fitted with a Finnigan EI/CI ion source.
Samples were introduced to the mass spectrometer using the solids probe. The probe was heated gradually from 100 to 400 degrees. The instrument was used as a single quadrupole and scanned from 50 to 1000 daltons.