Analysis of Lipid Signaling Class Analytes Using a Travelling Wave Cyclic Ion Mobility Separator
Analysis of Lipid Signaling Class Analytes Using a Travelling Wave Cyclic Ion Mobility Separator
Authors: Emma Marsden-Edwards - Waters Advanced MS,Mike McCullagh - Waters,Johannes PC Vissers - Waters,Martin Plamer - Waters Advanced MS,James Langridge - Waters Advanced MS
Aims
Lipids are a diverse group of biomolecules and class separation is
achieved using chromatographic and MS based techniques; but is challenging
due to the chemical structure diversity and isobaric nature of lipids. IMS
enhances system peak capacity and improves isomer resolution. IM separation
was achieved using a multi-pass travelling-wave cyclic IM (cIM)-device, where
increasing the number of passes around the device increases both mobility
resolution and ion residence time. MS and CID fragmentation data were obtained
on precursor IM separated analytes followed by ToF mass measurement.
Results
Unsaturated free fatty acid (FA) standards, differing in chain length and
number of cis/trans configurations, steroid hormones (androgens), isomers
differing in the position of a functional group, and isobaric lipid mediators
(prostaglandins) were chosen to determine the degree of IM separation required
to separate isomers and isobars. Data were collected on a cyclic ion mobilityenabled
quadrupole time-of-flight (Q-cIM-oaToF) mass spectrometer.
Direct infusion cIM-MS measurements, showed cis oriented FAs to be more
compact than those with trans-orientations. A various number of cycles of the
cIM -device, were required to achieve similar IM separation for mono-unsaturated
FAs of differing chain length. Unsaturated FAs with two or more double bonds,
separated by two mid-chain carbons, could not be distinguished. Shorter,
structurally more rigid and compact FAs were discriminated at reduced
resolution. Following IM separation, isomeric FAs were successfully CID
fragmented and identified.
The analysis of an isobaric adrenal steroid pair, indicated an IM resolution
(Ω/ΔΩ) ≥ 200 was required to resolve them. Following IM separation, nearly
identical, but individual product ion spectra were readily detected. A three
compound isomer steroid mixture could be partially resolved using multi-pass IM.
The separation was sufficient to extract product ion spectra for the three
individual components and identify them using informatics methodology.
Conclusions
We demonstrate the utility of multi-pass Cyclic ion mobility-enabled
quadrupole time-of-flight (Q-cIM-oaToF) mass spectrometry experiments for the
analysis of isomeric lipid signalling analytes.