What absorbs at 3470 cm⁻¹ in an FTIR spectrum?
A band near 3470 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 3470 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) | 13 | 12 | 1.0 |
| Carbonyl (C=O) | 4 | 3 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| N h | 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 |
| Amine primary | 2 | 2 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 0 | 1.0 |
| Hydrogen bond | 1 | 0 | 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 |
|---|---|---|---|
| PMMA | 3470, 1722, 1383 | Carbonyl (C=O), Ester | 1 |
| Chitosan-Based | 3470, 2924, 1743 | Hydroxyl (O-H) | 1 |
| Al2O3 | 3470, 1722, 1383 | Hydroxyl (O-H), Carbonyl (C=O) | 1 |
| biodiesel | 3470, 858, 1457 | Carbonyl (C=O), Ester, Hydroxyl (O-H) | 1 |
| Chitosan | 3470, 1650, 1655 | Hydroxyl (O-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 3470 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
-
Hydroxyl (O-H) confidence 1.0
“Finally, a low absorbance increase was observed around 3470cm-1,correspondingtotheformationofhydroxylgroup(-OH)formedduringthermal oxidation.[9]”
Rohman 和 Man - 2013 - Application of FTIR Spectroscopy for Monitoring th DOI: 10.1080/10942912.2011.603874 -
Hydroxyl (O-H) confidence 1.0
“3482.84 Conversely, micron-size particle shows a single peak at 3470.31 This reveals the presence of OH group on the surface of filler which initiates an interaction to occur with lithium salt ions [16, 24].”
Effect of Al2O3 in poly(methyl methacrylate) composite polymer electrolytes DOI: 10.1063/1.5034559 -
Ester confidence 1.0
“show a narrow weak band in the region of 3400-3500 with maximum absorbance show a narrow weak band in the region of 3400-3500 cm-1, with maximum absorbance cm-1, wavenumbers around 3470 which are assigned to the overtone of the glyceride es”
Chitosan-Based Anti-Oxidation Delivery Nano-Platform: Applications in the Encapsulation of DHA-Enriched Fish Oil DOI: 10.3390/md19080470 -
Hydroxyl (O-H) confidence 1.0
“The signal for end-OH stretching of PCHC appeared near 3670 the signals at 3575 and 3470 cm-1 are overtones of the signals for free and intramolecularly Hcm-1 signals at 3575 and 3470 are overtones of the signals for free and intramolecular”
Du 等 - 2022 - Intraand Intermolecular Hydrogen Bonding in Misc DOI: 10.3390/ijms23137018 -
Acetate confidence 1.0
“The FTIR speccm-1 due trum of castor (4.6) indicates peak at 3470.0 cm-1 to - OH group, at 1743.9 due to -C=O group and cm-1 at 1167.6 due to C-O group.”
Kumar 等 - 2014 - Studies on carcinogenic PAHs emission generated by DOI: 10.2478/pjct-2014-0009 -
Amine primary confidence 1.0
“These bands, which are also present in the spectrum of the 4-aminothiophenol reactant, result from the presence of the covalently-bound aromatic modifier at the material cm-1), surface, and can be ascribed to aromatic primary amine N-H stre”
Systematic optimization of poly(vinyl chloride) surface modification with an aromatic thiol DOI: 10.1016/j.eurpolymj.2017.09.030 -
Hydroxyl (O-H) confidence 1.0
“A transient conditions, but carbonyl functionalities were pronounced shoulder of the broad hydroxyl band at 3470 cm-1 observed (Popovicheva et al., 2015a), we assign the band is related to aromatic amino N-H stretches.”
Popovicheva 等 - 2017 - Chemical Composition of DieselBiodiesel Particula DOI: 10.4209/aaqr.2017.04.0127 -
Ester confidence 1.0
“By comparing the spectra of crude and heated coffee oils in the region between 3600 and cm-1 cm-1, (Fig 1), there is a very small band around 3470 in crude oils, associated with 3100 the overtone of the glyceride ester carbonyl absorption [”
Investigation on Crude and High-Temperature Heated Coffee Oil by ATR-FTIR Spectroscopy along with Antioxidant and Antimicrobial Properties DOI: 10.1371/journal.pone.0138080
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