Ion characterisation by comparison of ion mobility spectrometry and mass spectrometry data

Abstract

The major uncertainty related to ion mobility spectrometry is the lack of knowledge about the characteristics of the ions detected. When using a radioactive atmospheric pressure ionisation source (e.g. 63 Ni), from theory proton bound water clusters are expected as reactant ions. When analyte ions occur, proton transfer should lead to proton-bound monomer and dimer ions. To increase the knowledge about those ionisation processes in an ion mobility spectrometer (IMS), a ß-radiation ionisation source was coupled to a mass spectrometer (MS) and an identical one to an IMS. Exemplarily, acetone, limonene and 2-and 5-nonanone were introduced into both instruments in varying concentrations. By correlating the MS and IMS spectra, conclusions about the identities of the ions detected by IMS could be drawn. Proton-bound monomer, dimer and even trimer ions (MH + , 2MH + , 3MH + ) could be observed in the MS spectra for acetone and 5-nonanone and could be assigned to the related signals detected by IMS. The oligomers could be expected from theory for increasing concentration. Limonene and 2-nonanone yielded in a variety of different ions and fragments indicating complex gas phase ion chemistry. Those findings on the obviously different behaviour of different analytes require further research focussed on the ion chemistry in IMS including the comparison of different ionisation sources.

Implementation of an Open-Source Multiplexing Ion Gate Control for High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS)

“…The performance of the Teensy coupled to the HiKE-IMS is evaluated by comparing Hadamard spectra with signal-averaged spectra for a number of small, volatile, flavor compounds. These compounds originate from a number of natural sources, including wood and various food stuffs, and may require an additional separation technique to IMS to identify in those complex matrices. − Various sequences and Hadamard parameters are examined and establish the groundwork, including discussion of assumptions and potential pitfalls, for implementing multiplexing on IMS platforms.…”

Making Every Single Puff Count—Simple and Sensitive E-Cigarette Aerosol Sampling for GCxIMS and GC-MS Analysis

“…Since the formation of these clusters depends on the substances present in the ionization area of the IMS, the spectrum of an IMS measurement contains different signals. These signals are primarily the reactant ions which are just the ionized water clusters and the various ionized analyte–water clusters which can contain one or more of the same or different analyte molecules, resulting in the formation of monomers and (mixed) dimers [ 43 , 44 , 45 ].…”