What absorbs at 3373 cm⁻¹ in an FTIR spectrum?
A band near 3373 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 3373 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) | 10 | 8 | 1.0 |
| N h | 5 | 5 | 1.0 |
| Amine primary | 2 | 2 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Sulfonate | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 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 |
|---|---|---|---|
| sodium alginate | 3373, 1636, 1080 | Hydroxyl (O-H), Alkyl C-H | 1 |
| carrageenan | 3373, 1156, 1100 | Hydroxyl (O-H), Alkyl C-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 3373 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
“withascorbicacid(a)andglutamine(b)areshowninFig.2.The cm(cid:2)1 January N-H absorption peak at 3373 was assigned to vibrations FTIR spectra of the SPUAA (a) and SPUGL (b) with 20 wt% HA.”
Cetina-Diaz 等 - 2014 - Physicochemical characterization of segmented poly DOI: 10.1039/c3tb21500h -
Amine primary confidence 1.0
“LLM confirmed rule peak-group candidate”
Synthesis, spectroscopic, thermal and structural properties of [M(3-aminopyridine)2Ni(μ-CN)2(CN)2]n (M(II)=Co and Cu) heteropolynuclear cyano-bridged complexes DOI: 10.1016/j.saa.2014.12.117 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Salem 等 - 2017 - Study of the effect of surface treatment of kenaf DOI: 10.1088/1742-6596/908/1/012001 -
Hydroxyl (O-H) confidence 1.0
“In the spectrum of the leaf part of the plant,1st peak (3372.57 cm-1) belongs to OH group in the group of (COOH), 2nd peak (2916.72-2848.93 cm-1, doublet) belongs to the group of NH 2, 3rd peak (1734.36 cm-1) belongs to C=O group in the gro”
Tasci 等 - 2016 - Determination of alliin and allicin in the plant o DOI: 10.17660/ActaHortic.2016.1143.19 -
Hydroxyl (O-H) confidence 1.0
“AC has characteristic spectra with a sharp absorption peak at 3373 Figure 3: FTIR spectra of (a) AC, (b) INA and (c) cm-1 indicating O-H stretching (free), aromatic NACINA cm-1, H stretching at 3363 C=O stretching at”
Wicaksono 等 - 2017 - Enhancement of solubility and dissolution rate of DOI: 10.4314/tjpr.v16i7.6 -
N h confidence 1.0
“3373cm-1 cm-1 and 3159-3298 assigned to groups NH and Figure1:HOMO-LUMOcategoriesoftheligands(mefenamicacid 1626cm-1 NH2, respectively;”
Abbas 等 - 2019 - Preparation, Diagnosis, Biological Activity, and T DOI: 10.1155/2019/8962923 -
Sulfonate confidence 1.0
“The peaks observed at 3373, 1221, 1037, 1157, 924 and 844 cm-1 can be attributed cm-1 1356-1374 attributed to sulphate (SO 3) group stretching in 1.5-3% CARR:SA (1:0) wafers.”
Akiyode 和 Boateng - 2018 - Composite Biopolymer-Based Wafer Dressings Loaded DOI: 10.3390/polym10080918 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils DOI: 10.3390/ijerph16244999
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