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Can ion mobility mass spectrometry and density functional theory help elucidate protonation sites in 'small' molecules?
Author(s) -
Lapthorn Cris,
Dines Trevor J.,
Chowdhry Babur Z.,
Perkins George L.,
Pullen Frank S.
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6700
Subject(s) - chemistry , ion mobility spectrometry , mass spectrometry , protonation , fragmentation (computing) , ion , tandem mass spectrometry , ion mobility spectrometry–mass spectrometry , molecule , analytical chemistry (journal) , polyatomic ion , computational chemistry , chromatography , selected reaction monitoring , organic chemistry , computer science , operating system
RATIONALE Ion mobility spectrometry‐mass spectrometry (IMS‐MS) offers an opportunity to combine measurements and/or calculations of the collision cross‐sections and subsequent mass spectra with computational modelling in order to derive the three‐dimensional structure of ions. IMS‐MS has previously been reported to separate two components for the compound norfloxacin, explained by protonation on two different sites, enabling the separation of protonated isomers (protomers) using ion mobility with distinguishable tandem mass spectrometric (MS/MS) data. This study reveals further insights into the specific example of norfloxacin and wider implications for ion mobility mass spectrometry. METHODS Using a quadrupole ion mobility time‐of‐flight mass spectrometer, the IMS and MS/MS spectra of norfloxacin were recorded and compared with theoretical calculations using molecular modelling (density functional theory), and subsequent collision cross‐section calculations using projection approximation. RESULTS A third significant component in the ion mobilogram of norfloxacin was observed under similar experimental conditions to those previously reported. The presence of the new component is convoluted by co‐elution with another previously observed component. CONCLUSIONS This case demonstrates the potential of combined IMS‐MS/MS with molecular modelling information for increased understanding of 'small‐molecule' fragmentation pathways. Copyright © 2013 John Wiley & Sons, Ltd.