What absorbs at 3433 cm⁻¹ in an FTIR spectrum?
A band near 3433 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 3433 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) | 21 | 21 | 1.0 |
| N h | 9 | 9 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Water (H2O) | 4 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Sulfonate | 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 |
|---|---|---|---|
| ZnO | 3433, 1400, 3430 | Hydroxyl (O-H) | 1 |
| nanocomposite | 3433, 2921, 3300 | Hydroxyl (O-H), N h, Carboxyl (COOH) | 1 |
| PMMA | 3433, 1722, 1383 | Carboxyl (COOH) | 1 |
| gold nanoparticles | 3433, 1638, 3252 | 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 3433 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
“cm-1 at 3433 in the FTIR spectra of pure PMMA is related to the N-H stretching vibration [25,26], and The band appeared at 3433 cm-1 in the FTIR spectra of pure PMMA is related to the N-H stretching cm-1 shifts to 3432 with a significant de”
Aziz 等 - 2017 - From Insulating PMMA Polymer to Conjugated Double DOI: 10.3390/polym9110626 -
Sulfonate confidence 1.0
“Then, the functional group of the cm-1 of the sulfonated group SPEEK was determined using Fourier transfer infrared (FTIR) showed O-H vibration at 3433 (SO2-OH).”
Hasbullah 等 - 2016 - Synthesis and Characterizations of Electrospun Sul DOI: 10.1063/1.4948867 -
Alkyl C-H confidence 1.0
“Ni-doped ZnO NP s O-H stretching 3433.68 3434.55 3432.89 C-H stretching”
Comparative study on dielectric and structural properties of undoped, Mn-doped, and Ni-doped ZnO nanoparticles by impedance spectroscopy analysis DOI: 10.1007/s10854-019-02517-0 -
confidence 1.0
“The peaks at 3433 is corresponds to N H 738, 584, 509 & 422 cm-1 is for stretching vibration of C C bonds of quiniod rings, stretching vibration 1556 04 14:53 at Laval] [Universite by Downloaded Figure 1.”
Patil 等 - 2011 - Electrical Conductivity of PolyanilineNiZnO3 Comp DOI: 10.1080/00150193.2011.620836 -
confidence 1.0
“of polyols on gluten cm(cid:1)1 Stretch vibration band of N-H was evident at 3433 for gluten (Fig.”
Interactions between polyols and wheat biopolymers in a bread model system fortified with inulin: A Fourier transform infrared study DOI: 10.1016/j.heliyon.2018. -
Hydroxyl (O-H) confidence 1.0
“cm-1 of 3000-3700 The band appearing at 3433 was corresponding to H-O-H stretching.”
A novel gallium oxide nanoparticles-based sensor for the simultaneous electrochemical detection of Pb2+, Cd2+ and Hg2+ ions in real water samples DOI: 10.1038/s41598-022-24558-y -
Acetate confidence 1.0
“The major peaks recorded in the pure DFX sample were attributed to the cm-1), cm-1), functional groups: -O-H stretching (3433 carboxylic -C=O stretching (1638 cm-1) cm-1), C-F stretching (1061 and C-Cl stretching (771 which confirms the pur”
Delafloxacin-Capped Gold Nanoparticles (DFX-AuNPs): An Effective Antibacterial Nano-Formulation of Fluoroquinolone Antibiotic DOI: 10.3390/ma15165709 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Al-Qahtani 等 - 2022 - Structural, morphological, optical and electrochem DOI: 10.15251/JOR.2022.182.187
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.