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Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry
J Larry Campbell1,2, Amy Meng-Ci Yang3, Luke R Melo3
1SCIEX, 71 Four Valley Drive, Concord, ON, Canada, L4K 4V8. larry.campbell@sciex.com.
Journal of the American Society for Mass Spectrometry
|April 21, 2016
Summary
Differential mobility spectrometry (DMS) enables studying tautomers. Hydrogen-deuterium exchange (HDX) can induce tautomerization, altering ion structures and requiring careful reagent selection for isomer analysis.
Area of Science:
- Analytical Chemistry
- Physical Chemistry
- Computational Chemistry
Background:
- Tautomeric species are challenging to study due to their elusive nature.
- Differential mobility spectrometry (DMS) offers a platform for isomer separation and interrogation.
- Gas-phase hydrogen-deuterium exchange (HDX) is a common technique for probing ion structure.
Purpose of the Study:
- To demonstrate the utility of DMS for studying tautomeric species.
- To investigate the impact of HDX on tautomer interconversion.
- To provide insights into the structural dynamics of 4-aminobenzoic acid tautomers.
Main Methods:
- Separation of N- and O-protonated 4-aminobenzoic acid tautomers using DMS.
- Application of gas-phase hydrogen-deuterium exchange (HDX) with varying D2O levels.
- Experimental monitoring of tautomer interconversion.
- Support from molecular dynamics and electronic structure calculations.
Main Results:
- DMS successfully separated N- and O-protonated 4-aminobenzoic acid tautomers.
- HDX with trace D2O showed differential exchange rates as expected.
- Higher D2O levels or basic reagents induced N- to O-protonated tautomer interconversion.
- Calculations indicated the onset of solution-phase properties with solvation.
Conclusions:
- HDX can induce tautomerization, altering ion structures.
- Judicious selection of HDX reagents and conditions is crucial when analyzing interconvertible isomers separated by DMS.
- DMS coupled with HDX and computational methods provides a powerful approach for studying tautomeric species.
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