What absorbs at 1269 cm⁻¹ in an FTIR spectrum?
A band near 1269 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 1269 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 |
|---|---|---|---|
| C-O single bond | 7 | 6 | 1.0 |
| Methoxy (OCH3) | 6 | 6 | 1.0 |
| Methacrylate | 6 | 6 | 1.0 |
| Acetate | 6 | 6 | 1.0 |
| Phosphate (PO4) | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Protein | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 0.8 |
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 |
|---|---|---|---|
| lignin | 1269, 1035, 1510 | Methacrylate, Acetate, C-O single bond | 2 |
| silver nanoparticles | 1269, 1636, 1631 | Methacrylate, Acetate, C-O single bond | 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 1269 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
-
Carbonyl (C=O) confidence 1.0
“the variability among the cell wall compositions, we choose not to modwalls were characterized by a set of bands corresponding to ify the default parameters even if the CART models could be improved cm-1) guaiacyl ring breathing with carbon”
Dinant 等 - 2019 - Synchrotron FTIR and Raman spectroscopy provide un DOI: 10.1093/jxb/ery396 -
Aromatic ring confidence 1.0
“+ 9 1270-1260 G ring C-O stretching in G rings 1269 1268 10 1110 Aromatic C H deformation of S rings 1112 1105”
Dong 等 - 2020 - Pyrolysis Products Distribution of Enzymatic Hydro DOI: 10.3390/catal10020187 -
Protein confidence 1.0
“LLM confirmed rule peak-group candidate”
The effect of hyperbaric oxygen therapy on bone macroscopy, composition and biomechanical properties after ionizing radiation injury DOI: 10.1186/s13014-020-01542-2 -
Lignin confidence 1.0
“Standard lignin showed strong absorption bands at 1269 cm-1 and 1210-1220 cm-1, cm-1 cm-1, Standard lignin showed strong absorption bands at 1269 and 1210-1220 assigned to the C-O group of guaiacyl, phenolic O-H, and ether in syringyl and g”
Enhancing Thermal and Mechanical Properties of Ramie Fiber via Impregnation by Lignin-Based Polyurethane Resin DOI: 10.3390/ma14226850 -
Acetate confidence 1.0
“cm-1 Moreover, the peak at 1269.04 represents the C-O stretch of the carboxylic acid group cm-1 attached to the benzene ring, while the peak at 706.59 shows C=C stretching of”
Biodegradation of Azo Dye Methyl Red by Pseudomonas aeruginosa: Optimization of Process Conditions DOI: 10.3390/ijerph19169962 -
Acetate confidence 1.0
“The band at 1269 could be assigned to transition, which demonstrate the presence of polyphethe C-O stretching vibration of carboxylic acids.”
Ismail 等 - 2019 - Medicago polymorpha-mediated antibacterial silver DOI: 10.1515/gps-2018-0030 -
Acetate confidence 1.0
“The aryl-alkyl ether functional appearance of peaks at 2173.8, 2123.6, and 2044.5 cm-1, group was found at the peak of 1269.2 which as attributed to the C-O-C stretching motion.”
James 等 - 2022 - Synthesis and Characterization of Novel Nano-carbo DOI: 10.15376/biores.17.3.4452-4469 -
Protein confidence 1.0
“Amide I + II/Hydroxyapatite (HA) (M:MI) (The ratio between integrated areas of amide I + II cm-1) cm-1)) (1520-1720 for HA (916-1180 and Amide III + Collagen/HA (M:MIII) (The cm-1) ratio between integrated areas of amide III (1210-1270 with”
Influence of hyperbaric oxygen on biomechanics and structural bone matrix in type 1 diabetes mellitus rats DOI: 10.1371/journal.pone.0191694
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