Professor Akos Vertes of George Washington University is supported by the Analytical and Surface Chemistry Program to study the formation of ions from molecules in liquids under electrospray conditions. In spite of the long history of work in this area as well as the importance of Electrospray Ionization Mass Spectrometry (ESI-MS) in bioanalysis, details of our understanding of the associated phenomena remain unresolved. This is due in part to the complicated electro-hydrodynamics that must be addressed more or less simultaneously. Additional complications have become apparent as our understanding of ionic solvation has become more sophisticated. Insight is sought into 1) dispersion of a liquid stream into electrically charged droplets and 2) the ultimate stage of liberation of sample ions from these droplets. One experiment is to modulate the electrospray using the spraying voltage in order to synchronize the spray with the repetitive introduction of ions into the time of flight mass analyzer. Phase Doppler anemometry, mass spectrometry and microscopic imaging are used to correlate (primary) droplet size and velocity distributions with the observed mass spectra. Molecular dynamics is used to study droplet breakup and ion formation.
John Fenn's recent Nobel Prize for Electrospray Ionization Mass Spectroscopy (ESI) is only the most public recognition of its impact, and in particular, its biochemical applications. Improved understanding of ESI is highly likely to lead to even more impact. In addition, this fundamental work on droplet and ion formation is likely to have scientific and technical impact in diverse processes such as formation of clouds, inhalation toxicology and drug delivery, nano-processing and manipulation, and printing.
