What absorbs at 3535 cm⁻¹ in an FTIR spectrum?
A band near 3535 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 7 cited sources
Quick answer
A band near 3535 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) | 6 | 6 | 1.0 |
| Fatty acid | 2 | 2 | 1.0 |
| N n bond | 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 |
|---|---|---|---|
| edible oils | 3535, 1743, 1064 | Fatty acid | 2 |
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 3535 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
“7 (2007) 721 cm-1 Mg2+ C is peaked at 3535 and is associated with OH ⎯ vibration perturbed by ions in the lattice.”
Choubey 等 - 2007 - Influence of doping on OH absorption in LiNbO3 cry DOI: 10.1002/crat.200610894 -
confidence 1.0
“The Fourier transform infrared (FTIR) spectra of these coesite crystals taken in the OH cm(cid:3)1, stretching region consist of two sharp peaks at 3535 and 3500 which were assigned previously to two different boron-based n n point defects,”
Deon 等 - 2009 - Coupled boron and hydrogen incorporation in coesit DOI: 10.1127/0935-1221/2009/0021-1843 -
Hydroxyl (O-H) confidence 1.0
“The mixture was titrated spectra of blending oil, cottonseed oil and CCl cm-1 was related to the O-H funcsorption band at 3535 with 0.01 M of potassium hydroxide and shaken vigorously tional groups present in oils, revealing the characteris”
Hu 等 - 2019 - Rapid Determination of Acid Value of Edible Oils v DOI: 10.5650/jos.ess18156 -
Fatty acid confidence 1.0
“3690cm(cid:1)1, the other two peaks, at 3618 and Notably, the use of the quartz cuvette can not only provide an are almost cm(cid:1)1 accurate and long optical path length for measuring the FTIR specunchanged, indicating that the band at 35”
Determination of the acid values of edible oils via FTIR spectroscopy based on the OH stretching band DOI: 10.1016/j.foodchem.2016.06.035 -
Hydroxyl (O-H) confidence 1.0
“The baseline points were optimized for each band: The oxidative stability of the fresh samples was determined by cm(cid:0) cm(cid:0) 1) 1, the alcohol band (3535 was measured using 4600 the hyRancimat (Oil Stability Index, OSI).”
A study of the dynamic changes of stability taking place during virgin olive oil storage period examined by mesh cell-FTIR spectroscopy DOI: 10.1016/j.lwt.2022.114160 -
Fatty acid confidence 1.0
“could be an indication that the production of free fatty acids and their ageing, as well as the intensity of the CO Moreover,theadditionalpresenceofthebandat3535cm-1suggested conversion into lead carboxylates did not occur at the same rate.”
Sotiropoulou 等 - 2018 - Advanced analytical investigation on degradation m DOI: 10.1016/j.microc.2018.03.007 -
Hydroxyl (O-H) confidence 0.9
“Explicitly assigned as OH stretching vibration in text.”
Del Vecchio 等 - 2019 - High-Temperature Evolution of Point Defect Equilib DOI: 10.3390/min9100574
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