WARF: P99352US

Reducing the Charges of Ions Generated by Electrospray Ionization for Mass Spectrometry


Lloyd Smith, Mark Scalf, Michael Westphall, Daniel Ebeling

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a device and method that makes it possible to analyze large molecules, such as DNA, by mass spectrometry.
OVERVIEWMass spectrometry provides a rapid and sensitive means to detect a wide variety of molecules. Analysis by this technique requires that molecules first be converted to gas-phase ions. Converting small molecules to ions is straightforward; however, ionizing large molecules, such as DNA, wasn’t possible until the advent of electrospray ionization (ESI) and MALDI (matrix-assisted laser desorption-ionization) techniques. ESI avoids the fragmentation of analyte molecules that occurs with MALDI. But ESI generates ions carrying multiple charges, with the number of possible charge states increasing with molecule size. As a result, the mass spectra of these ions tend to be extremely complex and difficult to interpret.
THE INVENTIONUW-Madison researchers have developed a device and method to reduce the charge state of ions produced by electrospray ionization, making it possible to analyze large molecules, such as DNA, by mass spectrometry. In this method, ESI is used to convert macromolecules into ions carrying multiple charges. Next, these ions undergo reactions with bipolar ions generated from a polonium alpha particle source. This charge reduction process creates ions carrying mostly single charges, greatly simplifying data analysis once the ions are analyzed by mass spectrometry.
  • Mass spectrometric analysis of large biomolecules like DNA
  • Allows rapid mass spectrometric analysis of mixtures of DNA, peptides and other large biomolecules
  • Could open new opportunities for the use of mass spectrometry in genomics and proteomics
  • Technique has been successfully used to analyze molecules up to 16 kDA
  • Requires very few changes to standard mass spectrometry procedures
  • Adds little additional cost to conventional ESI
  • Causes minimal fragmentation of molecules during the ionization process
Contact Information
For current licensing status, please contact Jennifer Gottwald at or 608-960-9854.
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