What absorbs at 3353 cm⁻¹ in an FTIR spectrum?
A band near 3353 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 3353 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) | 9 | 8 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Carbohydrate | 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 |
| Amide | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 0 | 1.0 |
| Silicon (Si) | 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 | 3353, 1650, 1655 | Alkyl C-H, Methacrylate, Hydroxyl (O-H) | 1 |
| polystyrene | 3353, 1020, 1600 | Alkyl C-H, Methacrylate, Hydroxyl (O-H) | 1 |
| copper oxide | 3353, 624, 1686 | Hydroxyl (O-H), Alkyl C-H, Methacrylate | 1 |
| copper oxide nanoparticles | 3353, 624, 1317 | Hydroxyl (O-H), Alkyl C-H, Methacrylate | 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 3353 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
“e and CH stretching of pure CMC at 3353 and 2921 respectively.”
Guben 和 Ege - 2019 - Physico-chemical Effects of Gelatin Addition in Ca DOI: 10.1557/adv.2019.239 -
Acetate confidence 1.0
“Moreover, Cannizzaro reaction of DAS in a concentrated sodium hydroxide cm-1 cm-1 the absorption peaks at 3353 and 1642 in MNPs/DAS spectrum were as well as C=O stretching of carboxyl group in hydroxy acid of attributed to OH”
Synthesis of a Magnetic Nanoparticles/Dialdehyde Starch‐based Composite Film for Food Packaging DOI: 10.1002/star.201800035 -
Hydroxyl (O-H) confidence 1.0
“The band at 3353 is due to stretching vibration of O-H which cmindicates the presence of alcoholic groups in crocin.”
Lee 等 - 2015 - ATR-FTIR and Spectrometric Methods for the Assay o DOI: 10.1080/10942912.2014.923911 -
Carbohydrate confidence 1.0
“The absorbance peaks at cm-1 3353, 2898, 1434, 1382, and 895 are associated with cellulose I.”
Lu 等 - 2020 - One-pot Green Synthesis of Carboxylated Cellulose DOI: 10.1016/j.biortech.2007.04.029 -
Hydroxyl (O-H) confidence 1.0
“Furthermore, Figure 4 shows that no O-H groups in Styrofoam, which was found also Furthermore, Figure 4 shows that no O-H groups in Styrofoam, which was found cm-1) in brackish water Styrofoam, where peaks (3353 began to form with low inten”
Interaction between Styrofoam and Microalgae Spirulina platensis in Brackish Water System DOI: 10.3390/toxics9030043 -
Hydroxyl (O-H) confidence 1.0
“cm-1 at 450 and OH stretching at 3353 In Figure 2d, the absorption peak situated at 450 cm-1 corresponds to the Cu-O stretching and the one at 3353 is due to the OH stretching vibration.”
Green and Traditional Synthesis of Copper Oxide Nanoparticles—Comparative Study DOI: 10.3390/nano10122502 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Kuen 等 - 2017 - Increased Loading, Efficacy and Sustained Release DOI: 10.3390/nano7110379 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
On the Use of OPEFB-Derived Microcrystalline Cellulose and Nano-Bentonite for Development of Thermoplastic Starch Hybrid Bio-Composites with Improved Performance DOI: 10.3390/polym13060897
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