Table 2 Main peaks in HTS-FTIR spectra of fungi
Spectral range | Wavenumbers (cm−1) | Group and class | Assignment | Remarks |
|---|---|---|---|---|
Lipid region I (3050–2800 cm−1) | 2955 | CH3 functional group in aliphatic compounds | C-H asymmetrical stretching | Hydrocarbon chain length in lipids |
2930, 2925 |  > CH2 functional group in aliphatic compounds | |||
2885–2865 (2855 in our case) | CH3 functional group in aliphatic compounds | C-H symmetrical stretching | Hydrocarbon chain length in lipids | |
2870–2840 |  > CH2 functional group in aliphatic compounds | |||
3010 | =C-H functional group in aliphatic compounds | =C–H stretching | Unsaturation index in lipids | |
Lipid region II (1800–1700 cm−1) | 1745, 1742 | Carboxylic group in triglycerides | C=O stretching | Total lipid content (frequency decreases with chain length) |
1708, 1710 | C=O group in carboxylic acid dimers | C=O stretching | Free fatty acids | |
Amide region (1700–1500 cm−1) | 1670–1630 (1650) | C=O groups in primary and secondary amides | C=O stretching | Amide I band |
1610–1570 | Carboxylate group | Antisymmetric COO− stretching | Ionized free fatty acids | |
1560–1530 | –CO–NH– groups in primary and secondary amides | Coupled in-plane N–H bending and C–N stretching | Amide II band | |
Mixed region (1500–1200 cm−1) | 1480–1440 | Methyl groups | CH3 antisymmetric bending | Lipids |
1480–1440 | Methylene groups | CH2 bending | Lipids | |
1380–1360 | Aliphatic compounds | Symmetric CH3 bending | Lipids | |
1280–1070 | C–O–C in esters, ethers, lactones | C–O–C antisymmetric stretching | Polysaccharides | |
Carbohydrate region (1200–700 cm−1) | 1280–1220 | Phosphodiester bonds in nucleic acids | P=O asymmetrical stretching | Polyphosphate |
1050–1000 | Alkyl aryl ethers | C–O–C stretching | Polysaccharides | |
740–720 | Methylene groups in aliphatic compounds (hydrocarbons and lipids) | CH2 rocking in hydrocarbon chains | Intensity increases with the increasing chain length |