Fig. HSQC Spectrum of Aromatic Region for Oven Dried lignin reference sample 0-1
Fig. HSQC Spectrum of Aliphatic Region for Oven Dried lignin reference sample 0-1
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Aromatic Region:
The HSQC spectra indicate clear and well-preserved signals for guaiacyl (G) and syringyl (S) units, especially the S2,6 peaks. This preservation demonstrates minimal structural alterations in the lignin aromatic units due to moderate drying temperatures. There is no significant broadening of peaks, suggesting that the lignin's native structure remains largely intact under this condition.
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Aliphatic Region:
Prominent methoxy (OMe) and side-chain linkages, including β-O-4 and β-β, are visible, indicating minimal degradation. This confirms that the drying process at 105°C is mild enough to avoid substantial cleavage of aliphatic ether bonds.