What absorbs at 2927 cm⁻¹ in an FTIR spectrum?
A band near 2927 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 2927 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 | 81 | 75 | 1.0 |
| Hydroxyl (O-H) | 16 | 15 | 1.0 |
| Amide | 6 | 6 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| Carboxyl (COOH) | 5 | 5 | 1.0 |
| Acetate | 5 | 5 | 1.0 |
| Methyl | 4 | 4 | 1.0 |
| Ketone | 4 | 4 | 1.0 |
| Ester | 4 | 4 | 1.0 |
| Carbonyl (C=O) | 4 | 4 | 1.0 |
| Aromatic ring | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Water (H2O) | 3 | 3 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| Fatty acid | 2 | 2 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Carbohydrate | 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 |
|---|---|---|---|
| starch | 2927, 1650, 1540 | Hydroxyl (O-H), Methacrylate, Alkyl C-H | 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 2927 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
-
Alkyl C-H confidence 1.0
“The luminescent properties cm-1 peak at 2927 corresponds to the C-H stretching vibraof ZrO are greatly affected by these intrinsic defects as they 2 cm-1 tions [39] and the observed peak at 2348 is related to introduces the donor or accepte”
Study of Copper Doped Zirconium Dioxide Nanoparticles Synthesized via Sol–Gel Technique for Photocatalytic Applications DOI: 10.1007/s10904-020-01616-4 -
Alkyl C-H confidence 1.0
“The stretching of hydroxyl group (─OH) of starch was presented by a peak at 3291 cm-1 whereas the starch methyl group at 3291cm-1 2927 cm-1.”
Ashri 等 - 2018 - Modified Dioscorea hispida starch-based hydrogels DOI: 10.1016/j.ijbiomac.2017.10.125 -
Alkyl C-H confidence 1.0
“cm-1 3435 the diffraction angles of and The reason for could be attributed to O-H stretching, while cm-1 thisphenomenonisthatthecrystalstructureofstarchinthe 2927 was the C-H asymmetric stretching vibration abcommercialbabyricenoodlesissign”
Cao 等 - 2020 - Optimization of the preparation process of mung be DOI: 10.1515/ijfe-2020-0025 -
Alkyl C-H confidence 1.0
“The cm-1, The NK native rice starch had a wider peak at 2927 which was due to the stretching vibration peak of C-H (Figure 4).”
Formation of Intermediate Amylose Rice Starch–Lipid Complex Assisted by Ultrasonication DOI: 10.3390/foods11162430 -
Alkyl C-H confidence 1.0
“Between them, the spectra of LBQ had two peaks at 2972 cm-1 (C-H stretching of the methylene bridges) and 2927 cm-1 (C-H stretching vibration) [41-43], and the absorbance of LBG and LBN was only at 2928 or 2927 cm-1, respectively.”
Comparative Analysis of the Phenolic Profile of Lycium barbarum L. Fruits from Different Regions in China DOI: 10.3390/molecules27185842 -
Water (H2O) confidence 1.0
“1599 1599 1598 1598 Vibrations of water molecule 2927 2927 2926 2918 Hydrogen bonding 3592 3592 3594 3593 Fundamental stretchingof hydroxyl”
Gold nanoparticles assisted surface enhanced Raman scattering and luminescence of Er3+ doped zinc–sodium tellurite glass DOI: 10.1016/j.jlumin.2014.11.032 -
Alkyl C-H confidence 1.0
“strain NRS_38 (Figure 5A) is related to the C-H stretching of the -CH3 group in fatty acids, while the peaks around 2927.30 and Carbon Source Strain NRS_35 (mg/L) Strain NRS_38 (mg/L)”
Characterization of Polyhydroxybutyrate, PHB, Synthesized by Newly Isolated Haloarchaea Halolamina spp. DOI: 10.3390/molecules27217366 -
Alkyl C-H confidence 1.0
“2011) and the abcm-1 sorption peak at 2927 was due to symmetric stretching -CH of (Pan et al.”
Effect of aluminum modification of rice straw–based biochar on arsenate adsorption DOI: 10.1007/s11368-020-02595-2
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.