Table 1.
GC‐FID RFs of thioacidolysis/Raney‐Ni dimers (I–XII) and their yields (μmol g−1 KL[a] or CEL lignin) from softwood samples.
| Dimers | RFs | Loblolly pine CW | White spruce CW | Loblolly pine CEL | White spruce CEL | Spruce MWL[c] | |
|---|---|---|---|---|---|---|---|
| β–5 | I | 0.92 | 55.7 | 49.8 | 40.0 | 45.0 | |
| II | 0.92 | 5.4 | 6.8 | 3.6 | 5.4 | ||
| III | 0.87 | 7.8 | 7.1 | 3.2 | 4.9 | ||
| IV | 1.07 | 2.0 | 1.6 | 1.1 | 1.1 | ||
| V | 0.95 | 36.8 | 13.3 | 15.9 | 23.8 | ||
| VI | 1.05 | 1.1 | 25.1 | 15.0 | 2.1 | ||
| total | I–VI | 108.8 | 103.7 | 78.6 | 82.3 | 65 | |
| RR [%] | 44.5 | 45.2 | 44.7 | 46.5 | 31 | ||
| β–1 | VII | 0.92 | 51.2 | 48.3 | 35.0 | 32.5 | |
| VIII | 0.94 | 8.8 | 10.3 | 11.1 | 7.4 | ||
| total | VII–VIII | 60.0 | 58.6 | 46.1 | 39.9 | 66 | |
| RR [%] | 24.5 | 25.5 | 26.2 | 22.5 | 31 | ||
| β–β | IX | 1.15 (1.26)[b] | 0.9 | 1.2 | 0.9 | 1.1 | – |
| X | 1.17 (1.02)[b] | 0.3 | 0.4 | 0.1 | 0.2 | – | |
| total | IX–X | 1.2 | 1.6 | 1.0 | 1.3 | – | |
| RR [%] | 0.5 | 0.7 | 0.6 | 0.7 | – | ||
| 4–O–5 | XI | 1.05 | 19.4 | 15.6 | 15.2 | 16.1 | 16 |
| RR [%] | 8.0 | 6.8 | 8.6 | 9.1 | 8 | ||
| 5–5 | XII | 0.87 | 55.1 | 49.9 | 35.1 | 37.5 | 62 |
| RR [%] | 22.5 | 21.8 | 19.9 | 21.2 | 30 | ||
| total | I–XII | 244.5 | 229.4 | 176.0 | 177.1 | 209 | |
[a] KL=Klason (acid‐insoluble) Lignin; KL contents for loblolly pine CW, white spruce CW, loblolly pine CEL, and white spruce CEL are 27.5, 28.6, 90, and 88 %, respectively. [b] RFs of IX and X were determined from their selected‐ion chromatograms; m/z 385, 439, and 386 were chosen for IX, X, and XIII, respectively. [c] Yields are from reported data.7b Relative ratios (RR) for each dimer are their percentages relative to the total identified dimers in this study. In addition, the GC–FID RF of XIII versus docosane is 1.12.