What absorbs at 1337 cm⁻¹ in an FTIR spectrum?
A band near 1337 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 1337 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 |
|---|---|---|---|
| Alkyl C-H | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Phospholipid | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 0.9 |
| Carbonate | 1 | 1 | 0.9 |
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 |
|---|---|---|---|
| cellulose | 1337, 1735, 1650 | Alkyl C-H, Methacrylate, C-O single bond | 2 |
| polyethylene | 1337, 1737, 1720 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 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 1337 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
“The bands at 1337 1263, or 71311,26 cm(cid:1)1, a change of the conformation of CH 2OH at C-6 from all assigned as C-O-H bending, are also”
Oh 等 - 2005 - Crystalline structure analysis of cellulose treate DOI: 10.1016/j.carres.2005.08.007 -
Amide confidence 1.0
“5) are attributed to the in amide I band, a 1337 band has been used to identify collagen glycosaminoglycan bands.”
Organic biopolymers of venus clams: Collagen-related matrix in the bivalve shells with crossed-lamellar ultrastructure DOI: 10.1016/j.bbrep.2021.100939 -
Amide confidence 1.0
“Its presence interferes with the detection of the Amide III series of bands (1337, 1284, 1240 Methods).”
Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level DOI: 10.3390/molecules25184295 -
C-O single bond confidence 1.0
“Therefore, the ratio 3 cm-1 cm-1 2995 cm-1 to those at 1337 cm-1 due to C-OH in-plane stretching can be used to quantify of the absorbance at 4000-2995 to those at 1337 due to C-OH in-plane stretch-”
Quantitative Measurements of DP in Cellulose Paper Based on Terahertz Spectroscopy DOI: 10.3390/polym15010247 -
Acetate confidence 1.0
“absorption bands at peaks of 1717.47 while the peaks of CH2 bending were observed at 1473.52 The peak of 1337.39 cm(cid:0) cm(cid:0) cm(cid:0) 1 1 1 C-O and 1393.87 observed attributed to the CH3 bend.”
Evaluation of microplastics isolated from sea cucumber A caudina molpadioides in Pulau Langkawi, Malaysia DOI: 10.1016/j.heliyon.2023.e16822 -
Ring structure confidence 1.0
“adenosine and guanosine internal ring vibration gives rise to a peak at 1484 and at 1337 cm-1 Finally, a small component at approximately 1250 can be assigned to adenine, guanine and cm-1 thymine internal ring vibrations combined with N-H b”
FTIR Spectroscopy to Reveal Lipid and Protein Changes Induced on Sperm by Capacitation: Bases for an Improvement of Sample Selection in ART DOI: 10.3390/ijms21228659 -
confidence 1.0
“with the first overtone of the band appearing at 1337 whereas in the remaining one, which was found mode.18 +N-H(cid:1)(cid:1)(cid:1)O 1411.”
Rozenberg 等 - 2005 - A correlation between the proton stretching vibrat DOI: 10.1039/B503644E -
Lipid confidence 1.0
“cm-1 cm-1) The fingerprint spectral region (1800 to 850 showed that the absorbance spectra of the malignant and benign tissues were significantly distinct from each other, specifically at 1452cm-1/1452 cm-1, cm-1/1401 cm-1, cm-1/1337 cm-1,”
Detection of breast cancer by ATR-FTIR spectroscopy using artificial neural networks DOI: 10.1371/journal.pone.0262489
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