What absorbs at 3440 cm⁻¹ in an FTIR spectrum?
A band near 3440 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 3440 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) | 55 | 50 | 1.0 |
| Water (H2O) | 14 | 13 | 1.0 |
| N h | 12 | 10 | 1.0 |
| Alkyl C-H | 7 | 6 | 1.0 |
| Hydrogen bond | 4 | 4 | 1.0 |
| Methacrylate | 4 | 3 | 1.0 |
| Acetate | 4 | 3 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 2 | 1.0 |
| Urethane | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Phenolic | 2 | 2 | 0.9 |
| Ketone | 2 | 1 | 1.0 |
| Ester | 2 | 1 | 1.0 |
| Carbonyl (C=O) | 2 | 1 | 1.0 |
| Amide | 2 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Thiocyanate | 1 | 1 | 1.0 |
| Urea | 1 | 1 | 0.9 |
| Lignin | 1 | 1 | 0.7 |
| Secondary amine | 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 |
|---|---|---|---|
| chitosan | 3440, 1650, 1655 | Alkyl C-H, Hydroxyl (O-H), N h | 1 |
| starch | 3440, 1650, 1540 | Hydroxyl (O-H), Alkyl C-H | 1 |
| chitin | 3440, 1650, 1655 | Alkyl C-H, N 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 3440 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
-
Water (H2O) confidence 1.0
“carried out for GO and GT shown in Figure 4, both diffraction pattern shows common peaks corresponding to (002), (110), Superimposed FTIR spectra of GO and GT are shown in cm(cid:0) 1 GO.[38-40] and (101) standard diffraction peaks for Figu”
Enhanced Electrochemical NO2−Oxidation Reactions on Biomolecule Functionalised Graphene Oxide DOI: 10.1002/slct.202100608 -
confidence 1.0
“(2009b) observed vacancies, which have slower inherent diffusion), while bulk hydrogen diffusion an order of magnitude slower in Jaipur is dominated by hydrogen incorporated in the faster the Fe-bearing diopside, which contains peaks at 344”
Site-specific hydrogen diffusion rates during clinopyroxene dehydration DOI: 10.1007/s00410-016-1262-8) -
Hydroxyl (O-H) confidence 1.0
“The peak at 3440 corresponds to O-H stretching of the alcohol and phenol 53 cm-1 groups, N-H stretching of proteins, and adsorbed water.”
Hassanien 等 - 2019 - Novel green route to synthesize cadmium oxide@grap DOI: 10.1088/2053-1591/ab23ac -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Structural and spectroscopic studies of rare earths doped ceria (RELa,Sc,Yb_CeO2) nanopowders DOI: 10.1016/j.ceramint.2014.01.076 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Antimicrobial Activity of Chemically and Biologically Treated Chitosan Prepared from Black Soldier Fly (Hermetia illucens) Pupal Shell Waste DOI: 10.3390/microorganisms9122417 -
Hydroxyl (O-H) confidence 1.0
“Moreover, the presence of another 3 cm-1, broad peak assigned to O-H stretching, located at 3440 is noted.”
New Er3+ doped antimony oxide based glasses: thermal analysis, structural and spectral properties DOI: 10.1016/j.jallcom.2015.07.113 -
Hydroxyl (O-H) confidence 1.0
“All spectra have a hydroxyl ( OH) peak The titration curve for protonated peels shows a rapid decline ∼3440cm-1, alkyl ( CHn) peak at wave number at wave number aroundpH4,6and10.Thissuggeststhattherearefunctionalgroups 2935cm-1, 1750cm-1 ∼2”
Schiewer 和 Balaria - 2009 - Biosorption of Pb2+ by original and protonated cit DOI: 10.1016/j.cej.2008.05.034 -
confidence 1.0
“The bands at 3317, 3412, 3440 cm-1 and 3464 correspond to the symmetric and asymmetric N-H stretching bands which cm-1 are observed at 3329 and 3428 in pristine urea (Yue, Jia et al.”
Ternary Natural Deep Eutectic Solvent (NADES) Infused Phthaloyl Starch as Cost Efficient Quasi-Solid Gel Polymer Electrolyte DOI: 10.1016/j.carbpol.2017.03.023
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