Table 2.
Transmittance bands correlated to the corresponding wave numbers representing the functional organic groups present in the SC-CO2 extracts of Orthosiphon stamineus.
| Vibrational frequency (cm−1) | Samples | Corresponding organic groups |
|---|---|---|
| 3600–3200 (broad) | A3, B3, and C3 | O–H stretching |
| 2950–2800 | All nine samples | C–H stretching |
| 1780–1720 (sharp) | All nine samples | C=O stretching |
| 1660–1650 (weak) | C1, C2, B3 and C3 | C=C stretching |
| 1610–1600 (Sharp) | C1, A2, C2, A3, B3 and C3 | NO2– stretching |
| 1480–1460 | All nine samples | C–H bending (deformation) |
| 1385–1370 | All nine samples | C–C, C–H, O–H and C–O bending |
| 1240–1160 | All nine samples except B2 | C–C, C–O, C–N stretching |
| 1100–1090 | All nine samples except B2 | C–C, C–O, C–N stretching |
| 1050–1045 | All nine samples except A1 | C–C, C–O, C–N stretching |
| 960–900 | All nine samples | C–H bending |
| 710–725 | All nine samples | C–H bending |