What absorbs at 3426 cm⁻¹ in an FTIR spectrum?
A band near 3426 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 3426 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 |
| N h | 3 | 3 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 0.9 |
| Phenolic | 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 |
|---|---|---|---|
| Chitosan | 3426, 1650, 1655 | Hydroxyl (O-H), N h, C-O single bond | 1 |
| Polyamide | 3426, 1663, 1541 | N h | 1 |
| Silver nanoparticles | 3426, 1636, 1631 | Hydroxyl (O-H), N h, C-O single bond | 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 3426 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
“intensityshows the presence of the aliphatic -CH of DVB-1 shows the absorption peak at 3425.6 cm-1 cm-1;”
Aritonang 等 - 2019 - Grafting of Oleic Acid On Cyclic Natural Rubber Re DOI: 10.13005/ojc/350119 -
N h confidence 1.0
“In general, chitosan powder show characteristic peaks at 3425.58 cm-1 cm-1 cm-1 (-OH and -NH stretching), 2877.79 (-CH stretching), 1651.07 (amide I/C=O stretching), 2 cm-1 cm-1 cm-1 1597.06 (amide II/-NH bending), 1072.42 (C-O-C stretching”
Cahyono 等 - 2018 - Characteristics of eugenol loaded chitosan-tripoly DOI: 10.1088/1757-899X/349/1/012010 -
confidence 1.0
“2950cm-1 and a broad are visualized bya small peak at about (ii) heat-treated 2O-doped The Ag sample reveals four discm-1 and intense band centered at 3426 and followed by two tinct crystalline phases, calcium phosphate (Ca 3P 2O 8) cm-1.”
Bioactivity Behavior of Multicomponent (P2O5 –B2O3- SiO2-Na2O-CaF2) Glasses Doped with ZnO, CuO or Ag2O and their Glass-Ceramics DOI: 10.1007/s12633-020-00571-6 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Chitosan Capped Copper Oxide Nanocomposite: Efficient, Recyclable, Heterogeneous Base Catalyst for Synthesis of Nitroolefins DOI: 10.3390/catal12090964 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Goswami 等 - 2004 - One-pot synthesis of a novel water-soluble fullere DOI: 10.1021/cm0350232 -
Chitosan confidence 1.0
“Based on the FTIR spectra of the cm-1 chitosan membrane in Figure 2 showed that it has a wide absorption at 3425.58 that indicates the cm-1 vibration stretching -OH group.”
Hastuti 和 Assya'adha - 2020 - Synthesis and Characterization of Chitosan Membran DOI: 10.1088/1757-899X/833/1/012068 -
confidence 1.0
“The major peaks at 3426 and 1641 correspond to N-H of amines or O-H stretch of carboxylic acid,”
Paper wasp nest-mediated biosynthesis of silver nanoparticles for antimicrobial, catalytic, anticoagulant, and thrombolytic applications DOI: 10.1007/s13205-016-0459-x -
Hydroxyl (O-H) confidence 1.0
“This is indeed what we are observing in the infrared spectrum of chitosan-calcite composite, the single broad cm-1 peak at 3425.8 is assigned to be the stretching vibrations of both O-H and N-H cm-1 bonds, and the absorption of 2926.1 is cl”
Understanding the Interfacial Interactions of Bioinspired Chitosan-Calcite Nanocomposites by First Principles Molecular Dynamics Simulations and Experimental FT-IR Spectroscopy DOI: 10.1016/j.carbpol.2019.115054
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.