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Gas‐phase protomers of p ‐(dimethylamino)chalcone investigated by travelling‐wave ion mobility mass spectrometry ( TWIMS )
Author(s) -
Erabelli Ramu,
Xu Sihang,
Attygalle Athula B.
Publication year - 2018
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.4265
Subject(s) - chemistry , ion mobility spectrometry , ion , gas phase , mass spectrometry , ionization , chalcone , helium , phase (matter) , population , analytical chemistry (journal) , chromatography , stereochemistry , organic chemistry , demography , sociology
Results from ion‐mobility (IM) separation experiments demonstrate that O ‐ and N ‐protomers of p ‐(dimethylamino)chalcone ( p ‐DMAC) can coexist in the gas phase. The relative populations of the two protomers strongly depend on the ion‐generating settings and the conditions the precursor ions experience from the point of their gas‐phase inception to the time of their detection. Under relatively dry source conditions, the ratio of the gas‐phase protomers generated under helium‐plasma ionization (HePI) conditions is biased towards the thermodynamically favored O ‐protomer. However, when the humidity of the enclosed ion source was increased, the IM arrival‐time distribution profile of the mass‐selected protonated precursor of p ‐DMAC changed rapidly to one dominated by the N ‐protomer. Under spray‐ionization conditions, the formation of the thermodynamically less favored protomer has been generally attributed to a phenomenon called kinetic trapping. Herein, we demonstrate that the population of thermodynamically less favored N ‐protomer can be dramatically increased simply by introducing water vapor to the HePI ion source.