Charge assisted laser desorption/ionization mass spectrometry of droplets

  • Kaveh Jorabchi
  • Michael S. Westphall
  • Lloyd M. SmithEmail author


We propose and evaluate a new mechanism to account for analyte ion signal enhancement in ultraviolet-laser desorption mass spectrometry of droplets in the presence of corona ions. Our new insights are based on timing control of corona ion production, laser desorption, and peptide ion extraction achieved by a novel pulsed corona apparatus. We demonstrate that droplet charging rather than gas-phase ion-neutral reactions is the major contributor to analyte ion generation from an electrically isolated droplet. Implications of the new mechanism, termed charge assisted laser desorption/ionization (CALDI), are discussed and contrasted with those of the laser desorption atmospheric pressure chemical ionization method (LD-APCI). It is also demonstrated that analyte ion generation in CALDI occurs with external electric fields about one order of magnitude lower than those needed for atmospheric pressure matrix assisted laser desorption/ionization or electrospray ionization of droplets.


External Electric Field Laser Desorption Corona Discharge Ring Electrode Blunt Probe 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© American Society for Mass Spectrometry 2008

Authors and Affiliations

  • Kaveh Jorabchi
    • 1
  • Michael S. Westphall
    • 1
  • Lloyd M. Smith
    • 1
    Email author
  1. 1.Department of ChemistryUniversity of Wisconsin-MadisonMadisonUSA

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