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International Journal of Interdisciplinary Research

Table 2 Functional groups of purified blue pigment from FTIR Spectra

From: Extraction of Indigo dye from Couroupita guianensisand its application on cotton fabric

Wave number (cm−1) Functional group with mol. motion Std. synthetic indigo Purified blue pigment
3020-3000 Aromatics C-H Stretch 3018.39 3020.32
3400-2400 Carboxylic acids O-H Stretch 2399.28 2399.00
1640-1500 Amines N-H bend 1618.17 1519.80
1430-1290 C-H in-plane bend 1425.00 1425.30
1320-1210 Carboxylic acids (C-O stretch) 1215.07 1215.07
860-680 (s) Aromatic C-H bending 754.12 757.97
730-550 C-Cl stretch, acid chloride 669.25 669.25