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Table 5 Main assignments of lignin, polysaccharide and protein Fourier transform infrared bands.a

From: Advanced biorefinery in lower termite-effect of combined pretreatment during the chewing process

  Wavenumbers (cm-1) Assignments
Lignin  
1 1714 to 1725 Stretching of C = O unconjugated to aromatic rings (oxidized side-chains)
3 1655 Stretching of C = O conjugated to aromatic rings
4 1594 to 1609 Aromatic ring vibrations and C = O stretching
6 1504 to 1515 Aromatic ring vibrations
7 1462 to 1464 Asymmetric C-H bending (in CH3 and -CH2-)
8 1421 to 1424 Aromatic ring vibrations
10 1365 Symmetric deformation of C-H in methyl groups
11 1360 Phenolic hydroxyl vibrations
12 1270 (shoulder) Vibrations of guaiacyl rings and stretching vibrations of C-O bonds
13 1216 to 1225 C-C, C-O and C = O stretching (G condensed > G etherified)
14 1160 Deformation vibrations of C-H bonds on benzene rings
16 1090 to 1075 Deformation vibrations of C-O bonds in secondary alcohols and aliphatic ethers
17 1030 to 1033 Deformation vibrations of C-H bonds in aromatic rings
Polysaccharide  
9 1370 Symmetric bending of aliphatic C-H
15 1030 to 1170 C-O stretching in alcohols
18 890 β-Glycosidic linkages in pyranose units
Protein  
2 1655 to 1658 C = O stretching in amides (I)
5 1516 C = O stretching in amides (II)
  1. aReferred to references 32 to 34.