Table 2.
Retention times, relative abundances, assignment of pyrolysis products to guaiacyl-type (G), syringyl-type (S) and p-coumaryl/hydroxyphenyl (H) units and respective S/G ratios in original Iroko sawdust (OrigIR), original mixed sawdust of Iroko–Norway spruce (OrigIRNS), respective isolated Acidolysis lignin fractions (AL-IR, AL-IRNS) and acidolysis residues (ResIR, ResIRNS). PS indicates polysaccharides origin, EX indicates extractives origin. * compounds no. 65 and 66 in Faix et al. [30].
| Iroko | Iroko–Norway Spruce | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Peak # | Pyrolysis Product | Origin | RT (min) | OrigIR (%) | AL-IR (%) | ResIR (%) | OrigIRNS (%) | AL-IRNS (%) | ResIRNS (%) |
| 1 | Phenol | H | 19.35 | 0.8 | 0.4 | 0.4 | 0.7 | 0.6 | 0.5 |
| 2 | Guaiacol | G | 19.51 | 7.4 | 5.0 | 5.7 | 10.2 | 16.4 | 10.0 |
| 3 | 4-Methylphenol | H | 22.35 | 0.0 | 0.3 | 0.0 | 0.0 | 1.3 | 0.0 |
| 4 | 4-Methylguaiacol | G | 23.29 | 2.3 | 2.6 | 6.0 | 20.4 | 20.0 | 7.8 |
| 5 | 4-Ethylphenol | H | 25.41 | 0.0 | 1.7 | 0.0 | 0.0 | 0.5 | 0.0 |
| 6 | 4-Ethylguaiacol | G | 26.22 | 1.4 | 3.6 | 1.0 | 1.5 | 6.1 | 0.7 |
| 7 | 4-Vinylguaiacol | G | 28.18 | 14.8 | 14.1 | 12.2 | 15.2 | 17.6 | 14.5 |
| 8 | 4-Vinylphenol | H | 28.46 | 4.4 | 11.2 | 4.9 | 3.5 | 3.5 | 2.1 |
| 9 | Eugenol | G | 28.89 | 0.9 | 0.9 | 1.0 | 1.8 | 2.8 | 2.1 |
| 10 | 4-Propylguaiacol | G | 28.95 | 0.0 | 0.0 | 0.0 | 0.7 | 3.7 | 0.0 |
| 11 | Syringol | S | 30.03 | 8.5 | 5.6 | 8.3 | 4.5 | 4.3 | 6.5 |
| 12 | Isoeugenol (cis) | G | 30.77 | 0.6 | 1.1 | 0.5 | 0.8 | 2.1 | 0.9 |
| 13 | Isoeugenol (trans) | G | 32.46 | 5.8 | 9.7 | 6.6 | 9.5 | 13.4 | 9.9 |
| 14 | 4-Methylsyringol | S | 32.99 | 6.3 | 4.4 | 11.4 | 3.3 | 4.7 | 6.8 |
| 15 | Vanillin | G | 33.18 | 3.7 | 2.5 | 3.1 | 5.6 | 1.0 | 4.6 |
| 16 | Resorcinol | Ex | 34.82 | 1.0 | 11.3 | 0.0 | 0.0 | 1.7 | 0.0 |
| 17 | Homovanillin | G | 35.42 | 1.5 | 3.7 | 2.2 | 1.4 | 0.0 | 2.3 |
| 18 | 4-Ethylsyringol | S | 35.55 | 3.9 | 7.4 | 2.0 | 1.4 | 1.8 | 1.5 |
| 19 | Acetoguaiacone | G | 35.71 | 2.9 | 3.0 | 2.8 | 2.9 | 0.6 | 3.4 |
| 20 | 4-Vinylsyringol | S | 37.00 | 16.6 | 9.7 | 12.6 | 8.6 | 2.5 | 8.0 |
| 21 | Guaiacylacetone | G | 37.31 | 2.5 | 3.3 | 2.0 | 2.2 | 0.1 | 2.3 |
| 22 | 4-Allylsyringol | S | 37.54 | 2.8 | 3.2 | 2.5 | 1.2 | 1.1 | 1.8 |
| 23 | Coniferyl alcohol (cis) | G | 38.59 | 0.6 | 0.0 | 0.0 | 0.6 | 0.0 | 1.2 |
| 24 | 4-Propenylsyringol (cis) | S | 39.35 | 1.1 | 2.1 | 1.1 | 0.5 | 0.3 | 0.8 |
| F | C11H12O3 * | 39.73 | 4.2 | 2.3 | 0.9 | 0.7 | 0.0 | 0.0 | |
| 25 | Levoglucosane | PS | 40.19 | 1.2 | 0.0 | 5.2 | 3.0 | 0.0 | 11.6 |
| 26 | 4-Propenylsyringol (trans) | S | 40.73 | 7.5 | 10.5 | 8.8 | 3.0 | 0.6 | 5.0 |
| 27 | Syringaldehyde | S | 41.44 | 1.8 | 1.6 | 2.5 | 0.5 | 0.0 | 1.3 |
| 28 | Acetosyringone | S | 43.35 | 2.0 | 1.7 | 1.1 | 0.7 | 0.0 | 1.3 |
| 29 | Coniferyl alcohol (trans) | G | 43.97 | 1.0 | 0.0 | 2.0 | 1.1 | 0.0 | 2.3 |
| 30 | Coniferaldehyde | G | 44.43 | 0.7 | 0.9 | 2.4 | 0.9 | 0.0 | 2.4 |
| 31 | Syringylacetone | S | 44.68 | 3.0 | 1.7 | 2.0 | 0.9 | 0.0 | 1.4 |
| S/G ratio | 1.16 | 0.92 | 1.11 | 0.33 | 0.18 | 0.53 | |||