Ion Formation in Ion Mobility-Mass Spectrometry

This project is focused on understanding the formation of gas phase ions relevant to the detailed chemical analysis of complex samples of natural and biological origin. The project combines theoretical calculations of chemical structures of small molecules with experimental analytical measurements using ion mobility-mass spectrometry (IM-MS), which is a state-of-the art analytical technology. The project can be broken into two aspects: firstly, involving the computational prediction of molecular ion conformations using quantum mechanical methods. Individual compounds and also larger families of compounds have been selected to build up fundamental knowledge needed for testing and validation of theoretical predictions using experimental measurements. Compounds have been chosen to represent the broad chemical variety encountered in complex samples and therefore addressing the some of the most experimentally challenging applications addressed by analytical chemistry. Secondly, the analytical technology IM-MS will be employed for experimental measurements of these compounds. Ion mobility is used as an additional separation technology for the characterisation of compounds in the form of gas phase ions. IM-MS principally allows two important pieces of information to be determined for every compound measured within the sample an ion mobility, and an ion mass. Both of these properties are used to describe each measured compound and thereby improve the ability to distinguish and identify a hitherto unknown compound from the 1000s of other compounds present in complex samples of natural origin. While IM-MS is now a state-of-the-art analytical technology that can be applied for understanding complex environmental, biological, and chemical systems, fundamental knowledge on the ion formation process is currently lacking. The project aims to address this need by developing a fundamentals-driven knowledge base that can be used to improve the study of complex samples whereby 1000s of unknown compounds must be distinguished and, when possible, identified from within a single analysis.

This project developed our knowledge of the mechanisms of ion formation in ESI and APCI ion sources and made a significant contribution to the fundamental understanding of mass spectrometry (MS). This mass spectrometry project has a potential impact on other domains or sectors including scientific education, and routine applications of MS outside of academic research as we developed methods for the characterization of compounds that either have applications in industry and pharmaceutics (aminobenzoic acid derivatives, for example), or are of interest due to their impact on human health and our environment (polycyclic aromatic amines and polycyclic aromatic hydrocarbons).