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Sulfolane-Induced Supercharging of Electrosprayed Salt Clusters: An Experimental/Computational Perspective
- Source :
- Chemistry Publications
- Publication Year :
- 2021
- Publisher :
- Scholarship@Western, 2021.
-
Abstract
- It is well-known that supercharging agents (SCAs) such as sulfolane enhance the electrospray ionization (ESI) charge states of proteins, although the mechanistic origins of this effect remain contentious. Only very few studies have explored SCA effects on analytes other than proteins or peptides. This work examines how sulfolane affects electrosprayed NaI salt clusters. Such alkali metal halide clusters have played a key role for earlier ESI mechanistic studies, making them interesting targets for supercharging investigations. ESI of aqueous NaI solutions predominantly generated singly charged [NanI(n-1)]+ clusters. The addition of sulfolane resulted in abundant doubly charged [NanI(n-2)Sulfolanes]2+ species. These experimental data for the first time demonstrate that electrosprayed salt clusters can undergo supercharging. Molecular dynamics (MD) simulations of aqueous ESI nanodroplets containing Na+/I- with and without sulfolane were conducted to obtain atomistic insights into the supercharging mechanism. The simulations produced [NanIi]z+ and [NanIiSulfolanes]z+ clusters similar to those observed experimentally. The MD trajectories demonstrated that these clusters were released into the gas phase upon droplet evaporation to dryness, in line with the charged residue model. Sulfolane was found to evaporate much more slowly than water. This slow evaporation, in conjunction with the large dipole moment of sulfolane, resulted in electrostatic stabilization of the shrinking ESI droplets and the final clusters. Hence, charge-dipole stabilization causes the sulfolane-containing droplets and clusters to retain more charge, thereby providing the mechanistic foundation of salt cluster supercharging.
- Subjects :
- chemistry.chemical_classification
Ions
Aqueous solution
Cluster chemistry
Electrospray ionization
010401 analytical chemistry
Evaporation
Salt (chemistry)
Liquids
Metal clusters
010402 general chemistry
01 natural sciences
0104 chemical sciences
Cluster ions
chemistry.chemical_compound
Molecular dynamics
Chemistry
chemistry
Structural Biology
Computational chemistry
Alkali metal halide
Cluster (physics)
Sulfolane
Spectroscopy
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Chemistry Publications
- Accession number :
- edsair.doi.dedup.....092a64e1d0bfef91326c17e223b9f19d