Table 2 Relative contribution (%) and structural indices calculated from spectral data of main C structures over chemical shift regions (ppm) of 13C CPMAS-NMR spectra of HA-LIG and HA-CYN.

From: Antiflammatory activity and potential dermatological applications of characterized humic acids from a lignite and a green compost

 

Carboxyl-C

Phenol-C

Aryl-C

O-Alkyl-C

Methoxyl-C

Alkyl-C

Structural indexes

 

190–160

160–145

145–110

110–60

60–45

45–0

HB/HIa

A/OAb

ARMc

LigRd

HA-LIG

6.1

9.6

33.0

12.8

9.8

28.7

2.49

2.27

1.02

1.06

HA-CYN

10.9

5.7

20.0

27.5

13.8

22.2

0.92

0.81

0.52

2.43

  1. aHB/HI = hydrophobicity index = [Σ (0–45) + (110–160)/ Σ (45–60) + (60–110) + (160–190)].
  2. bA/OA = alkyl/O-alkyl ratio (0–45)/(60–10).
  3. cARM = aromaticity index [(110–160)/Σ (0–45) + (60–110)].
  4. dLigR = Lignin ratio (45–60)/(140–160).
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