What absorbs at 2932 cm⁻¹ in an FTIR spectrum?
A band near 2932 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 2932 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 | 40 | 40 | 1.0 |
| Hydroxyl (O-H) | 7 | 7 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Hydrogen bond | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Ring 6m | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 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 |
|---|---|---|---|
| glycerol | 2932, 1585, 1630 | Methacrylate, Alkyl C-H, Methoxy (OCH3) | 1 |
| silver nanoparticles | 2932, 1636, 1631 | Hydroxyl (O-H), Alkyl C-H, Methacrylate | 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 2932 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
“Appearance of a peak (cm-1) at 2932 (aliphatic C-H stretching mode) in Transmission Electron Microscopy analysis the FTIR spectrum of the same PF was consistent (TEM) with the above conclusions.”
Preparation and evaluation of nanocomposites of polyfuran with Al2O3 and montmorillonite clay DOI: 10.1002/pi.1562 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Dual Modification of Sago Starch via Heat Moisture Treatment and Octenyl Succinylation to Improve Starch Hydrophobicity DOI: 10.3390/polym14061086 -
Alkyl C-H confidence 1.0
“however, in contrast to bare (dcm-1, ) CH stretching band at 2932 the antisymmertic”
Farrag 等 - 2012 - Preparation and Spectroscopic Properties of Monola DOI: 10.1021/jp210453v -
Alkyl C-H confidence 1.0
“The determination of DEE was conducted in cm-1 absorption at 2931.80 wavelength correspond to triplicate to ensure their reproducibility of results and stretching vibration of C-H [23],[28].”
Preparation of In Situ Cross - Linked N - Maleoyl Chitosan - Oxidized Sodium Alginate Hydrogels for Drug Delivery Applications DOI: 10.3889/oamjms.2019.850 -
Hydroxyl (O-H) confidence 1.0
“A band was observed at 2932 which to the symmetric stretching of R-O-H.”
Green Synthesis of Silver Nanoparticles for Preparation of Gelatin Films with Antimicrobial Activity DOI: 10.3390/polym14173453 -
Amide confidence 1.0
“Both ASC and PSC have a weak absorption peak at the amide B band at cm-1, 2931.67 indicating the asymmetric stretching vibration of -CH [57].”
Song 等 - 2019 - Physicochemical and Biocompatibility Properties of DOI: 10.3390/md17030137 -
Alkyl C-H confidence 1.0
“The two peaks at cm-1 cm-1 2931.8 and 2879.4 were indicative of -C-H stretching (Rani et al.”
Tee 等 - 2017 - Chemical, Physical, and Barrier Properties of Edib DOI: 10.1016/j.jfoodeng.2011.11.010 -
Acetate confidence 1.0
“cm-1 carbonyl stretching vibration (C=O) which occurred at 1720 The peak at 1099 cm-1 corresponded to C-O-C stretching vibration and the peaks at 2932 and 2974 are assigned to sp3 -CH bond respectively.”
Influence of the synthesis parameters on the properties of natural rubber grafted poly-3-hydroxybutyrate (acte de congrès - 10 pages) DOI: 10.1088/1757-899X/509/1/012024
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