What absorbs at 2926 cm⁻¹ in an FTIR spectrum?
A band near 2926 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 2926 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 | 91 | 84 | 1.0 |
| Hydroxyl (O-H) | 14 | 13 | 1.0 |
| Methyl | 8 | 8 | 1.0 |
| Methoxy (OCH3) | 6 | 6 | 1.0 |
| Methacrylate | 6 | 6 | 1.0 |
| Acetate | 6 | 6 | 1.0 |
| Hydrogen bond | 5 | 5 | 1.0 |
| Amide | 5 | 5 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Carbohydrate | 4 | 4 | 1.0 |
| N h | 4 | 4 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| Lipid | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
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 |
|---|---|---|---|
| zinc oxide | 2926, 1627, 1638 | Alkyl C-H, 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 2926 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
-
N h confidence 1.0
“the samples with PG and the highest value in the FG sample, that is, 2923.74, 2926.15, from the CN stretch, CCN deformation and in-plane NH bending modes and is mostly cm-1 cm-1, 2927.71, and 2924.77 cm-1 for PG-FG 0-100, PG-FG 50-50, PG-FG”
Application of Poultry Gelatin to Enhance the Physicochemical, Mechanical, and Rheological Properties of Fish Gelatin as Alternative Mammalian Gelatin Films for Food Packaging DOI: 10.3390/foods12030670 -
Alkyl C-H confidence 1.0
“They observed vibrations of C-H functional groups at 2856.67 cm-1 and 2926.11 cm-1.”
The Effect of High-Intensity Ultrasound and Natural Oils on the Extraction and Antioxidant Activity of Lycopene from Tomato (Solanum lycopersicum) Waste DOI: 10.3390/antiox11071404 -
Hydroxyl (O-H) confidence 1.0
“O-H C-H 3562 stretching 2926 stretching 52.3742 0.1771 12.82 27.12 O-H”
El Bialy 等 - 2020 - Comparative Toxicological Effects of Biologically DOI: 10.2147/IJN.S241922 -
Alkyl C-H confidence 1.0
“The IR band at 2926 is assigned to the cm-1 C-H stretching vibration.”
Gani 等 - 2017 - Physico-chemical, structural, pasting and thermal DOI: 10.1016/j.ijbiomac.2016.10.100 -
Alkyl C-H confidence 1.0
“As a result, their cm-1) (~1157cm-1) corresponding ν(C-H) stretches (~2926 and (C-H) deformations can M.contortum contribute to the intensity increase of CH in NP4 treatment for [59,60].”
Response to nutrient variation on lipid productivity in green microalgae captured using second derivative FTIR and Raman spectroscopy DOI: 10.1016/j.saa.2021.120830 -
Alkyl C-H confidence 1.0
“Strain NRS_35 (mg/L) Strain NRS_38 (mg/L) 2925.87 cm-1 were generated by the symmetric stretch of C-H bond in CH2 groups.”
Characterization of Polyhydroxybutyrate, PHB, Synthesized by Newly Isolated Haloarchaea Halolamina spp. DOI: 10.3390/molecules27217366 -
Carboxyl (COOH) confidence 1.0
“30 peaks at 3288.63 represents for alcoholic group, OH stretch, 2926.01 for carboxylic acid OH 31 32 Accepted stretch, 1597.06 for aliphatic nitro compounds, and 1379.10 for organic sulfates in the region of 33”
Kalpana 和 Rajeswari - 2018 - Synthesis of palladium nanoparticles via a green r DOI: 10.1088/2053-1591/aaddef -
Metal oxygen confidence 1.0
“Earlier, the broad bands between 800cm(cid:2)1 the 500 and were attributed to the vibration of Zn-O 2926cm(cid:2)1 bond [30].”
Low temperature dielectric studies of zinc oxide (ZnO) nanoparticles prepared by precipitation method DOI: 10.1016/j.apt.2012.08.005
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