Field-induced droplet ionization mass spectrometry

A neutral droplet elongates along the axis of a strong electric field, ejecting opposing jets of positively and negatively charged progeny droplets. Images of droplets from a vibrating orifice aerosol generator illustrate this phenomenon, and mass spectrometric sampling of the progeny droplets demonstrates that they are a viable source of desolvated gas-phase ions. Field-induced droplet ionization (FIDI) mass spectra are presented for several species, including tetraheptylammonium cation, deprotonated benzene tetracarboxylic acid anion, and multiply protonated cytochrome c.