Table 3 Regions of interest in the FTIR spectrum of degrading leather, and how differently the time series trends cluster, depending on the pH of the surroundings conditions
Peak region of interest (cm−1) | Possible peak assignment | Cluster for pH 3 (see Fig. 6) | Cluster for pH 5 (see Fig. 6) |
|---|---|---|---|
3400–3600 | O–H stretch | 4 | 2 |
3200–3400 | O–H stretch | 6 | 1 |
2900–3100 | C–H stretch (lipids) | 4 | 2 |
1750 | C=O stretch | 1 | 7 |
1685 | Amide I | 8 | 7 |
1560–1590 | C–N–H, Amide II | 6 | 1 |
1490–1559 | C–N–H, Amide II | 7 | 8 |
1470–1490 | Amide III | 6 | 1 |
1257 | Amide III | 8 | 7 |
1030 | Tannin ester C–O–C=O stretch | 8 | 7 |
990 | Amide III | 8 | 7 |
Other regions | – | 5 | 3 |