What absorbs at 3375 cm⁻¹ in an FTIR spectrum?
A band near 3375 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 3375 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 | 10 | 1.0 |
| N h | 3 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Bromine | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Hydrogen 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 |
|---|---|---|---|
| TiO2 | 3375, 1700, 1093 | Hydroxyl (O-H), Carboxyl (COOH) | 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 3375 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
-
Hydrogen bond confidence 1.0
“LLM confirmed rule peak-group candidate”
Xiao 等 - 2020 - Preparation and characterization of broken-rice st DOI: 10.1016/j.ijbiomac.2020.05.182 -
Hydroxyl (O-H) confidence 1.0
“The absorption band at 3415 which was 3375cm-1 doled out to -OH group stretching vibration, moderately moved to with adding 1% wt of TiO 2.”
Gad 等 - 2021 - Synergistic Effect of Titanium Dioxide (TiO2) and DOI: 10.21203/rs.3.rs-161064/v2 -
Hydroxyl (O-H) confidence 1.0
“The IR (KBr disk) spectrum showed broad vibration 3375cm-1 proton at δ 5.73 (H-6) showed HMBC correlations with at attributed to hydroxyl moiety (OH), sharp H absorptionat1600cm-1attributedtoaromaticbenzenering, C-5, 7, and 8 at δ 156.8, 15”
Guyasa 等 - 2018 - Antibacterial Activity of Two Flavans from the Ste DOI: 10.1155/2018/5870161 -
Secondary amine confidence 1.0
“The begins to ongoing 3375cm-1 500° at condensation reaction at about is the absorption peak of secondary amine.”
Han 等 - 2018 - Synthesis and Performance of Functionalized alpha- DOI: 10.1155/2018/5873871 -
Hydroxyl (O-H) confidence 1.0
“[34], peaks at 3375 1647 1414 and 1080 are related to O-H”
Synthesis and Characterization of Exopolysaccharide Encapsulated PCL/Gelatin Skin Substitute for Full-Thickness Wound Regeneration DOI: 10.3390/polym13060854 -
Hydroxyl (O-H) confidence 1.0
“The band at 3375 corresponds to the O-H stretching cm-1 vibration of the hydroxyl groups.”
Deposition of TiO2 Thin Films on Wood Substrate by an Air Atmospheric Pressure Plasma Jet DOI: 10.3390/coatings9070441 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Johnsirani 等 - 2013 - DOI: 10.4152/pea.201302095 -
Acetate confidence 1.0
“adding NIC, blue shifts of wavenumbers occurred in both of the above bands: the stretching resonance of NH shifted Acknowledgment 3374.59cm-1 and C=O stretching vibration of amide I to 1647.79cm-1 band shifted to”
Liao 等 - 2016 - Probing into the Interaction of Nicotine and Bovin DOI: 10.1155/2016/9580136
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