What absorbs at 1508 cm⁻¹ in an FTIR spectrum?
A band near 1508 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
A band near 1508 cm⁻¹ is usually interpreted by checking which functional groups repeatedly co-occur there in the literature, then confirming at least one or two additional peaks in the same sample. This page ranks those assignments by accumulated evidence rather than by a single fixed textbook rule.
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Aromatic ring | 14 | 13 | 1.0 |
| Lignin | 8 | 8 | 1.0 |
| Methacrylate | 7 | 6 | 1.0 |
| Acetate | 7 | 6 | 1.0 |
| Carboxyl (COOH) | 6 | 5 | 1.0 |
| Amide | 6 | 5 | 1.0 |
| C c single bond | 6 | 4 | 1.0 |
| Alkene (C=C) | 5 | 5 | 1.0 |
| Carbonyl (C=O) | 5 | 4 | 1.0 |
| Ketone | 4 | 3 | 1.0 |
| Ester | 4 | 3 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 2 | 1.0 |
| Ring structure | 3 | 2 | 1.0 |
| Carbon dioxide | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Urethane | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 0.6 |
| Lipid | 1 | 1 | 0.6 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| polypropylene | 1508, 1030, 1600 | Methacrylate, Acetate | 1 |
| wood | 1508, 1740, 1730 | Lignin, Methacrylate, Acetate | 1 |
Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.
Spectrum logic
This band becomes meaningful only when read with its neighboring peaks. In practice, analysts first look at the assignments above, then check whether the same sample also shows other peaks expected for the same structural motif. A lone band near 1508 cm⁻¹ is usually not enough for material identification by itself.
Real-world usage
This type of query is common in polymer identification, unknown plastic screening, QC troubleshooting, recycled-material verification, and literature-backed peak assignment review.
Common mistakes
- Treating one isolated band as proof of a material without checking at least one or two supporting peaks.
- Ignoring overlap: multiple functional groups can contribute near the same wavenumber.
- Skipping validation when additives, blends, oxidation, or contamination may distort the spectrum.
Verification advice
When ambiguity remains, validate the hypothesis with DSC, GC-MS, or TGA, especially for blends, degraded samples, and filled polymers.
Literature behind these assignments
-
Acetate confidence 1.0
“cm-1 characteristic peak at 1735 (acetyl groups in xylan and other nonconjugated carcm-1 cm-1 bonyls), C=O stretch in xylan (hemicelluloses) and the peaks at 1508 and 1427 cm-1 cm-1 show the aromatic skeletal vibration of lignin.”
n-Heptadecane-Impregnated Wood as a Potential Material for Energy-Saving Buildings DOI: 10.3390/f13122137 -
Aromatic ring confidence 1.0
“cm-1, measuring 2800 to 3000 Another characteristic peak at 1735 including acetyl groups in xylan and other non-conjugated carbonyls, a C = O stretch in xylan (hemicellucm-1, loses), a lignin aromatic skeletal vibration at 1508 a lignin aro”
Can 等 - 2023 - Choline Chloride-Based Deep Eutectic Solvent-Treat DOI: 10.3390/f14030569 -
Alkyl C-H confidence 1.0
“For F-B fiber with the additional stretching, while bands at 895 show C-H deformacm-1 treatment of acidified NaClO 2, the peak at 1508 tion vibration [27] where small changes can be seen.”
Changes in bamboo fiber subjected to different chemical treatments and freeze-drying as measured by nanoindentation DOI: 10.1007/s10086-016-1590-3 -
Lignin confidence 1.0
“The lignin peak at 1508 cm-1 appears to be unchanged by the modification while the broad a large peak at 1730 assigned to stretch in ester groups [43-45].”
Leachability and Decay Resistance of Wood Polyesterified with Sorbitol and Citric Acid DOI: 10.3390/f11060650 -
Aromatic ring confidence 1.0
“the most pronounced peaks at around 1630, 1508, 1240, and 1040 The presence of a cm-1, relatively strong peak at around 1508 assigned to aromatic skeletal vibrations [61-63], indicates extended lignification of the cell wall in the collecte”
Cell Wall Properties Determine Genotype-Specific Response to Cold in Miscanthus giganteus Plants DOI: 10.3390/cells11030547 -
Hydroxyl (O-H) confidence 1.0
“The moderate bands in the 1508 cm-1 to 1156 region is attributed to O-H bending and symmetrical and asymmetrical C-O-”
Cai 等 - 2022 - Performance of Binderless Board Manufactured Using DOI: 10.15376/biores.17.4.6692-6705 -
Acetate confidence 1.0
“cm-1 lignin and hemicellulose was observed at 1734 The characteristic bands at 1508 cm-1 and 1263 were determined to be C=C, C-O stretching or bending vibrations of the cm-1, cm-1, cm-1 groups in lignin.”
Cresnar 等 - 2021 - Insight into the Surface Properties of Wood Fiber- DOI: 10.3390/polym13101535 -
Alkene (C=C) confidence 1.0
“The peak at 1608 as well as two remarkable shoulder peaks at 1508 and 1473 ascribed to stretching vibration of C=C in benzene rings.”
Fabrication of Glass Fiber Reinforced Composites Based on Bio-Oil Phenol Formaldehyde Resin DOI: 10.3390/ma9110886
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