Gas-phase ion mobility studies of constitutional isomeric hydrocarbons using different ionization techniques

We have investigated the influence of structural differences on the ionization pathways and drift behavior in ion mobility spectrometry for constitutional isomeric hydrocarbons. The ion mobility spectra of isomeric alkylated benzenes (C9H12 and C10H14) were recorded using photoionization, Ni-63 ionization and corona discharge ionization. Defined spectra for almost all isomeric compounds were observed using photoionization. When using this technique, no differences in ion mobility spectra of isomers can be observed. However, the methods of atmospheric-pressure chemical ionization (Ni-63 and corona discharge ionization) produce differences in ion mobility spectra or in the detectable concentration ranges of isomeric compounds depending on the number and position of aliphatic side chains. (C) 2001 Elsevier Science B.V.