List of LMs and LDs in oak wood classified using the PCA-QDA method. RDB = ring double bond equivalent.
| Compound | Retention time (min) | m/z ([M − H]−) | Δm (mDa) | Chemical formula | RDB | Concentrationa (μg g−1) |
|---|---|---|---|---|---|---|
| Vanillin | 1.26 | 151.0389 | 1.3 | C8H8O3 | 5 | 8 ± 3 |
| Acetosyringone | 1.63 | 195.0656 | 1.3 | C10H12O4 | 5 | — |
| Syringaldehyde | 1.64 | 181.0501 | 0.8 | C9H10O4 | 5 | 7 ± 2 |
| Coniferyl aldehyde | 1.74 | 177.0552 | 1.1 | C10H10O3 | 6 | 2.0 ± 0.2 |
| Cinnamic acid | 2.05 | 147.0449 | 1.5 | C9H8O2 | 6 | — |
| Sinapaldehyde | 2.13 | 207.0656 | 1.6 | C11H12O4 | 6 | 2.0 ± 0.6 |
| Unknown monomer I | 2.30 | 211.0605 | 0.9 | C10H12O5 | 5 | — |
| p-Hydroxybenzaldehyde | 2.51 | 121.0294 | 1.7 | C7H6O2 | 5 | — |
| Unknown monomer II | 3.09 | 191.0344 | 1.3 | C10H8O4 | 7 | — |
| Unknown monomer III | 3.20 | 227.0705 | 0.9 | C14H12O3 | 9 | — |
| Vanillic acid | 3.29 | 167.0346 | 0.9 | C8H8O4 | 5 | — |
| Syringic acid | 3.49 | 197.0449 | 0.6 | C9H10O5 | 5 | 4.30 ± 0.09 |
| Ferulic acid | 3.59 | 193.0500 | 0.7 | C10H10O4 | 6 | 1.00 ± 0.09 |
| Unknown dimer I | 4.55 | 317.1024 | 0.6 | C17H18O6 | 9 | — |
| Unknown dimer II | 4.90 | 385.0920 | 0.9 | C20H18O8 | 12 | — |
| Unknown dimer III | 5.02 | 359.1488 | 1.2 | C20H24O6 | 9 | — |
| Unknown dimer IV | 5.08 | 319.1175 | 1.2 | C17H20O6 | 8 | — |
| Unknown dimer V | 5.40 | 419.1708 | 0.3 | C22H28O8 | 9 | — |
| Unknown dimer VI | 6.33 | 303.0510 | 0.0 | C15H12O7 | 10 | — |
a
Concentrations based on external calibration and expressed in dry weight of sample.