What absorbs at 3424 cm⁻¹ in an FTIR spectrum?
A band near 3424 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 3424 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 17 | 17 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| N h | 4 | 4 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Ring 6m | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Protein | 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 |
|---|---|---|---|
| PVP | 3424, 2983, 1648 | Alkyl C-H, Hydroxyl (O-H), Amide | 1 |
| gold nanoparticles | 3424, 1638, 3252 | Amide, Alkyl C-H, Hydroxyl (O-H) | 1 |
| ZnO NPs | 3424, 1664, 875 | Alkyl C-H, Hydroxyl (O-H), Amide | 1 |
| silver nanoparticles | 3424, 1636, 1631 | Hydroxyl (O-H), Alkyl C-H, Amide | 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 3424 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
-
confidence 1.0
“The small peak at 3424 and 3112 But due to the hindrance from the (not N-H increased concentration of ZnO NPs in the gel cavity, in this shown) are assigned to the presence of stretching vibra-”
Chatterjee 等 - 2013 - Nanochannel morphology of polypyrrole-ZnO nanocomp DOI: 10.1039/c3ta12796f -
Hydroxyl (O-H) confidence 1.0
“1 3 3716 Journal of Inorganic and Organometallic Polymers and Materials (2021) 31:3711-3725 cm-1 corresponds to the O-H stretching peak at 3423.65 cm-1 vibrations of water molecules.”
Characterization, Antimicrobial and Antioxidant Evaluation of Biofabricated Silver Nanoparticles from Endophytic Pantoea anthophila DOI: 10.1007/s10904-021-01974-7 -
Protein confidence 1.0
“cm-1 The FTIR peaks at 3423.76, 2920.32, 2360.95 and 1635.69 attributed to the involvement of proteins in the AuNPs biofabrication and capping.”
Oladipo 等 - 2020 - Characterization and biomedical application of phy DOI: 10.1088/1757-899X/805/1/012021 -
Hydroxyl (O-H) confidence 1.0
“In detail, the intensity of the -OH and C=O groups shifted to 3424 cm-1 and 1735 due to bending of -OH and C=O groups on the surface of NASIF with 2N+ R(CH 3) sites of MB by electrostatic interactions and H-bonding [35].”
Adsorption of Methylene Blue by Biosorption on Alkali-Treated Solanum incanum: Isotherms, Equilibrium and Mechanism DOI: 10.3390/su14052644 -
Hydroxyl (O-H) confidence 1.0
“the hallmark of absorption bands at cm-1 3424 assigned to (O-H) overlapped with (N-H) stretching vibration [4, 22], cm-1 Also, the characteristic band at 2880 assigned to (C-H) stretching [22-24], cm-1 Also, the at 1653 assigned to C = O st”
Experimental and DFT studies on the structural and optical properties of chitosan/polyvinyl pyrrolidone/ZnS nanocomposites DOI: 10.1007/s00289-023-04700-0 -
N h confidence 1.0
“Explicitly assigned in text.”
Spectroscopic and Physicochemical Investigations of Azomethines with Triphenylamine Core towards Optoelectronics DOI: 10.3390/ma15207197 -
Hydroxyl (O-H) confidence 1.0
“The presence of both COOH and NH groups on the PAB3 copolymer was cm-1, confirmed by the intense broad band at 3424 which was attributed to the stretching vibration of both the OH and N-H groups.”
New Polymeric Adsorbents Functionalized with Aminobenzoic Groups for the Removal of Residual Antibiotics DOI: 10.3390/molecules27092894 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Facile biogenic fabrication of hydroxyapatite nanorods using cuttlefish bone and their bactericidal and biocompatibility study DOI: 10.3762/bjnano.11.21
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