A pulsed corona discharge switchable high resolution ion mobility spectrometer-mass spectrometer

A pulsed corona discharge ionisation source, a candidate replacement for Ni-63 ionisation sources for ion mobility spectrometry, is described along with a new design of ion mobility spectrometer-mass spectrometer. Preliminary research on the characterisation of the reactant ion peaks associated with the use of this ionisation source was undertaken by assembling a pulsed corona discharge ionisation switchable high-resolution ion mobility spectrometer-mass spectrometer to enable the mobility spectra, atmospheric chemical ionisation mass spectra and selected-mass mobility spectra to be obtained. With ammonia doping at 2.39 mg m(-3) in air and a water content of approximately 80 mg m(-3) in the positive mode the observed response was attributable to the formation of [(H2O)nNH(4)](+) and [(H2O)(n)(NH3)NH4](+) in the reaction region. The observed responses in the negative mode were more complex with evidence for the formation [(H2O)(n)O-2](-), [(H2O)(n)CO3](-), [(H2O)(n)HCO3](-), [(H2O)(n)CO4](-) and [(H2O)(n)NO3](-). The responses due to these species were clearly discernible in the resultant mobility spectra, with enough oxygen-based species formed to support analytically useful responses.