Table 2 Lignin inter-linkage proportions and syringyl-to-guaiacyl (S/G) ratio determined by 2D HSQC NMR spectroscopy
Biomass | Pretreatment | β-O-4′ linkages (per 100 aryl units) | β-5′ linkages (per 100 aryl units) | β-β′ linkages (per 100 aryl units) | S/G ratio |
|---|---|---|---|---|---|
Wheat straw | UNT | 46.10 | 4.46 | 3.81 | 0.67 |
DA | 14.85 | ND | ND | 0.64 | |
HW | 5.94 | 8.29 | ND | 1.02 | |
IL | 36.25 | 3.43 | 2.19 | 0.92 | |
CHLO | ND | ND | ND | ND | |
Miscanthus | UNT | 41.64 | 6.32 | 2.91 | 0.46 |
DA | 37.06 | ND | ND | 0.53 | |
HW | 13.77 | 9.79 | ND | 0.51 | |
IL | 46.61 | 6.52 | 2.93 | 0.53 | |
CHLO | ND | ND | ND | ND | |
Poplar | UNT | 54.66 | 5.92 | 6.06 | 1.08 |
DA | 39.66 | 5.99 | 10.76 | 0.56 | |
HW | 34.98 | 5.96 | 8.37 | 1.46 | |
IL | 59.99 | 4.75 | 7.38 | 1.22 | |
CHLO | ND | ND | ND | ND |