What absorbs at 3329 cm⁻¹ in an FTIR spectrum?
A band near 3329 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 3329 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) | 4 | 4 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| Cellulose | 3329, 1735, 1650 | Alkyl C-H, Hydroxyl (O-H), Carbohydrate | 1 |
| silver nanoparticles | 3329, 1636, 1631 | Hydroxyl (O-H), 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 3329 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
-
N h confidence 1.0
“cm-1 The vibrational bands at 3329 and 3193 corresponded to the stretching symmetThe vibrational bands at 3329 and 3193 cm-1 corresponded to the stretching symric vibration of NH and the bending symmetric vibration of NH for DES1, indicatin”
Can 等 - 2023 - Choline Chloride-Based Deep Eutectic Solvent-Treat DOI: 10.3390/f14030569 -
Hydroxyl (O-H) confidence 1.0
“Fourier Transform EFB WPG cm-1 Infrared spectrum shows that after the modification, the intensity of -OH peak at 3329 decreased and (FTIR) cm-1 the new peak at 1728 of C=O ester emerged.”
Jahi 等 - 2020 - Empty Fruit Bunch Cellulose based Sorbent for Oil DOI: 10.17576/jsm-2020-4909-29 -
Alkyl C-H confidence 1.0
“These values suggest how much stretching at 3329 C-H alkane stretching at”
Al-Ghouti 和 Dib - 2020 - Utilization of nano-olive stones in environmental DOI: 10.1007/s40201-019-00438-y -
confidence 1.0
“e PNX) for PN observed at 3329 represents the stretching vibration of the N-H bond, and the peak at about”
Lu 等 - 2016 - Use of polyurea from urea for coating of urea gran DOI: 10.1186/s40064-016-2120-x -
confidence 1.0
“It can be seen from Figure 5 that the N-H stretching produces symmetrical (3329 cm-1), asymmetrical (3251 and 3153 cm-1) stretching vibration peaks, and the vibration modes”
Facile Synthesis, Characterization, Anti-Microbial and Anti-Oxidant Properties of Alkylamine Functionalized Dumb-Bell Shaped Copper-Silver Nanostructures DOI: 10.3390/cryst10110966 -
Hydroxyl (O-H) confidence 1.0
“As observed in Figure 3A, a broad cm-1 peak at 3329 might correspond to the hydroxyl groups (-OH) in polyphenols in bush tea, such as flavonoids and phenolic acids or -NH stretch of amino groups [9].”
Biosynthesis of Silver Nanoparticles from Fermented Bush Tea (Athrixia phylicoides DC) Leaf Extract and Evaluation of Their Antioxidant and Antimicrobial Properties DOI: 10.3390/fermentation9070648 -
Hydroxyl (O-H) confidence 1.0
“FTIR spectra of new cellulose paper show absorbance cm-1 peaks located close to 3329 that represents an O-H functional group, located close to 2922 and cm-1 cm-1 2854 that represent a C-H functional group, and located close to 1050 that rep”
Fourier Transform Infrared (FTIR) Spectroscopy Analysis of Transformer Paper in Mineral Oil-Paper Composite Insulation under Accelerated Thermal Aging DOI: 10.3390/en11020364 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Pomelo Peel Modified with Citrate as a Sustainable Adsorbent for Removal of Methylene Blue from Aqueous Solution DOI: 10.3390/molecules23061342
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