What absorbs at 3335 cm⁻¹ in an FTIR spectrum?
A band near 3335 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 3335 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 | 9 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Urea | 1 | 1 | 1.0 |
| Urethane | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Silicon nitrogen | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Carbohydrate | 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 |
|---|---|---|---|
| polypropylene | 3335, 1030, 1600 | Methacrylate, Acetate, Hydroxyl (O-H) | 1 |
| LDPE | 3335, 1720, 1737 | Methacrylate, Acetate, 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 3335 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
-
Hydroxyl (O-H) confidence 1.0
“2), characterized by clear bands with a maximum of about 3335 corresponds to the stretching vibration of the -OH group of carbohydrates, water, and organic acids.”
Identification of sugars and phenolic compounds in honey powders with the use of GC–MS, FTIR spectroscopy, and X-ray diffraction DOI: 10.1038/s41598-020-73306-7 -
Chitosan confidence 1.0
“Similar peaks were also found in chitosan (3361cm-1, 2867cm-1), (3335cm-1, 2895cm-1) (3299cm-1, 2922cm-1 peanut shell and skin powder”
Meng 等 - 2020 - Effects of peanut shell and skin extracts on the a DOI: 10.1016/j.ijbiomac.2020.02.235 -
Acetate confidence 1.0
“In the present study, the cm(cid:1)1 symmetric NH2 CH3 stretching vibration is observed at 3335 in and CH group are not involved in the intermolecular hydrogen”
Growth, structure, Hirshfeld surface and spectroscopic properties of 2-amino-4-hydroxy-6-methylpyrimidinium-2,3-pyrazinedicorboxylate single crystal DOI: 10.1016/j.molstruc.2017.11.019 -
confidence 1.0
“FTIR analysis of the degraded LDPE films gives a close view of N-H cm-1, stretching of aldehyde group at 3334.92 and 3228.84 cm-1, C-C=C symmetric of aromatic ring at 1639.49 C=O cm-1, stretching of aldehyde group at 1735.93 peak at N=O”
Gajendiran 等 - 2016 - Microbial degradation of low-density polyethylene DOI: 10.1007/s13205-016-0394-x -
Hydroxyl (O-H) confidence 1.0
“A peak was observed at 3335 attributed to the hydroxyl (-OH) functional group.”
Experimental Study on the Application of Cellulosic Biopolymer for Enhanced Oil Recovery in Carbonate Cores under Harsh Conditions DOI: 10.3390/polym14214621 -
Silicon nitrogen confidence 1.0
“Peaks observed at 1175, 2200, and 3335 cm-1 refer to with the Si-N stretching mode [25].”
Examination of the Hydrogen Incorporation into Radio Frequency-Sputtered Hydrogenated SiNx Thin Films DOI: 10.3390/coatings11010054 -
Acetate confidence 1.0
“Figure 4b also shows a band at approximately 3335 cm-1, which may be associated with elongation in the HN-C=O group [71], confirming the presence of nitrogen detected in with elongation in the HN-C=O group [71], confirming the presence of n”
Simultaneous Treatment of Both Sides of the Polymer with a Conical-Shaped Atmospheric Pressure Plasma Jet DOI: 10.3390/polym15020461 -
Carboxyl (COOH) confidence 1.0
“The weak but characteristic peaks observed at 1581 (sh), 1541 cm-1 (also stronger in sample D13) are indicative of the antisymmetric carboxylate vibration of metal salts [3335], possibly due to interactions between Pb2+ and Ca2+ (due to lea”
Identification of Colourants and Varnishes in a 14th Century Decorated Wood-Carved Door of the Dionysiou Monastery in Mount Athos DOI: 10.3390/coatings11091087
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