Multistage Ion Mobility Spectrometry Combined with Infrared Spectroscopy for Glycan Analysis

The structural complexity of glycans makes their characterization challenging, not only because of the presence of various isomeric forms of the precursor molecule but also because the fragments can themselves be isomeric. We have recently developed an IMS-CID-IMS approach using structures for lossless ion manipulations (SLIM) combined with cryogenic infrared (IR) spectroscopy for glycan analysis. It allows mobility separation and collision-induced dissociation of a precursor glycan followed by mobility separation and IR spectroscopy of the fragments. While this approach holds great promise for glycan analysis, we often encounter fragments for which we have no standards to identify their spectroscopic fingerprint. In this work, we perform proof-of principle experiments employing a multistage SLIM-based IMS-CID technique to generate second-generation fragments, followed by their mobility separation and spectroscopic interrogation. This approach provides detailed structural information about the first generation fragments, including their anomeric form, which in turn can be used to identify the precursor glycan.

Automated summary

The complex structure of glycans poses challenges in their characterization due to the presence of isomeric forms and isomeric fragments. A new approach combining IMS-CID-IMS with cryogenic infrared spectroscopy for glycan analysis has been developed. However, the lack of standards for identifying spectroscopic fingerprints of fragments remains a challenge. In this study, a multi-stage SLIM-based IMS-CID technique was used to generate second-generation fragments for detailed structural analysis of the first generation fragments.