Abstract
ABSTRACT
Rationale
Comprehensive characterization of lignin‐derived oligomers remains a major analytical challenge because of their high structural diversity and the lack of methods capable of resolving native interunit linkages in complex biomass‐derived mixtures. Molecular‐level understanding of these oligomers is essential for elucidating lignin depolymerization mechanisms and guiding biomass valorization strategies.
Methods
Lignin oligomers generated from methanol‐based flow‐through solvolysis of birch sawdust were analyzed by high‐performance liquid chromatography coupled with ultraviolet detection and tandem mass spectrometry (HPLC‐UVD/MS
n
). Chromatographic separation was performed on tandem reversed‐phase C18 columns, and structural characterization was achieved using electrospray ionization Orbitrap mass spectrometry with higher‐energy collisional dissociation (HCD).
Results
Distinct chromatographic behaviors were observed for lignin‐derived products with different degrees of polymerization, enabling differentiation of monomeric and oligomeric species. Tandem MS analysis of representative oligomers revealed characteristic fragmentation pathways that enabled structural elucidation of oligomers. β‐O‐4 linkages were identified as the predominant interunit structures, and native β‐β motifs were also characterized.
Conclusions
Untargeted molecular‐level characterization of lignin‐derived products generated from methanol‐based flow‐through solvolysis of birch biomass provides direct insights into the composition and interunit linkages of native‐like lignin oligomers. These findings reveal the structural diversity of biomass‐derived oligomers and bridge the gap between model‐compound studies and real biomass‐derived lignin systems.