Resolving Isomeric Structures in Natural Complex Carbohydrates: A Comparative Study of SLIM and Cyclic Ion Mobility...

Area of Science:

• Analytical Chemistry
• Biochemistry
• Mass Spectrometry

Background:

• Recent advancements in ion mobility mass spectrometry (IMS) have introduced high-resolution techniques like cyclic IMS and structures for lossless ion manipulations (SLIM IMS).
• These platforms offer enhanced capabilities for distinguishing complex biomolecular conformations, crucial for detailed structural analysis.

Purpose of the Study:

• To evaluate and compare the performance of cyclic IMS and SLIM IMS for characterizing complex natural polysaccharides.
• To utilize homogalacturonan oligosaccharides (HGOS) from plant pectin as a model system for direct comparison of the two IMS technologies.

Main Methods:

• Enzymatic depolymerization of parent pectin to generate homogalacturonan oligosaccharides (HGOS) with varying degrees of polymerization (DP) and methylation (DM).
• Analysis of HGOS using both cyclic IMS and SLIM IMS platforms to generate mass spectra and ion mobility maps.
• Direct comparison of data obtained from identical HGOS species across both analytical platforms.

Main Results:

• The 10-m SLIM IMS demonstrated higher resolving power in single-pass analyses compared to cyclic IMS, separating more features for specific HGOS species.
• Multi-pass separations on cyclic IMS enabled resolution of features not discernible in single-pass mode.
• Distinct ion formation and charge state distributions were observed: SLIM IMS produced higher charged species and more cation adducts, potentially diluting sensitivity, while cyclic IMS favored lower charge states, simplifying interpretation.

Conclusions:

• Both cyclic IMS and SLIM IMS exhibit significant capabilities for resolving complex HGOS structures, demonstrating their complementary nature.
• Cyclic IMS is considered more practical for routine analysis due to factors including ionization behavior, instrument tuning, and data processing, despite SLIM IMS offering superior intrinsic resolution.