Department of Chemistry and Biochemistry
Physical Chemistry Seminar Series

Professor Evan R. Williams - UC Berkeley
Hosted by Jim Prell

Title: Overcoming Molecular Complexity One Ion at a Time

Heterogeneous materials can be challenging to analyze especially when the masses of individual components extend beyond 100 kDa.  With mass spectrometry, individual charge states produced by electrospray ionization can be difficult to resolve due to overlaps in m/z from other components or from adduction of salts or other non-specific molecular interactions.  One demonstrated solution to this problem of sample heterogeneity for high mass analytes is to measure the charge as well of the m/z of individual ions so that the mass of each ion can be determined without interference from other ions.  Single ion mass measurements have been performed with a variety of instrument types, but charge detection mass spectrometry with electrostatic ion traps have the advantage of virtually unlimited mass range, single charge accuracy, and the ability to make dynamic measurements.  A primary challenge is to acquire single ion data sufficiently rapidly to make this method practical.  Solutions to this challenge, as well as state of the art capabilities of charge detection mass spectrometry and applications to viral and nanoparticle analysis will be discussed. Results from experiments aimed at understanding the chemistry and physics of charged droplets will also be presented.