Table 3.

Fourier transform infrared spectroscopic analysis of chitosan extracted by the chemical method in reviewed articles.

	Vibration Modes
Reference	NH2, OH in Pyranose Ring (cm−1)	-NH Stretching (cm−1)	Symmetric (CH3) and Asymmetric (CH2) Stretching (cm−1)	Amide I Amide II ** and Amide III *** Bands (cm−1)	CH2 Bending and CH3 Deformation (cm−1)	CO Stretching (cm−1)	Ring Stretching (cm−1)
[8]	3438	---	2924	1421 ***	---	1075	896
[18]	3452.58	---	2924.01	1622.21 1550 **	1446	1078	875
[68]	3398	3262	---	1658	---	---	876
[45]	3846	3295	2878	1646 1537 **	1403	1018	---
[69]	3450.65	2852.72	2924.09	1629.85	---	---	---
[70]	3411	3425	2919	1651 1321 ***	1418	1078	899
[71]	3425	2881	2921-2879	1647.19 1559 **	---	---	---

--- No band found.