From spray stability to ion formation: contorted menisci and ion chemistry in electrosprays
Date:
Monday, October 15, 10:50 am
Symposium:
Fundamentals of Electrospray Ionization
Topic(s):
Mass Spectrometry Microfluidics Proteomics
Author(s):
Akos Vertes (presenting) - 1 Peter Nemes - 1 Ioan Marginean - 1 Samita Goyal - 1
Institution(s):
1. George Washington University
Abstract:
Electrosprays exhibit a wide array of spraying regimes. They are characterized by large differences in the electrohydrodynamic disintegration of the liquid, in the droplet size and velocity distributions of the spray plume and in the nature and abundance of the produced ions. They also show different stability toward inherent changes in environmental and spraying conditions. Therefore, understanding spraying regimes and their transformations is of importance for analytical applications.
We show that, in addition to the dripping, burst, pulsating, and cone-jet regimes, another ejection mode exists. In this astable regime the electrospray spontaneously switches between the pulsating and the cone-jet modes. With the introduction of this heretofore undescribed regime, a consistent view of the diverse axial regimes becomes possible, enabling their classification based on nonlinear dynamics. Electrosprays exhibit three main axial regimes, dripping, pulsating, and cone-jet, potentially separated by two chaotic regimes, burst and astable, respectively.
Of the axial spraying regimes the cone-jet mode appears to be most suited for ion production. Higher ion yields, a decreased extent of analyte fragmentation and oxidation are characteristic to this spraying mode. Thus in it the integrity of weak biologically relevant noncovalent complexes can also be preserved to a better degree. The effect of spraying mode changes is most prominent in the cone-jet mode, where the pH is expected to be lower than that of the bulk solution due to electrochemical oxidation of the solvent. In turn, proteins, sensitive to variations in the environment, undergo conformational changes, reflected by shifts in their charge state distributions. Our results suggest that improvements are achievable by the active control of the electrospray spraying regime.
Novelty of this Contribution:
Coherent view of electrospraying regimes and ion production is developed.
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