What absorbs at 3415 cm⁻¹ in an FTIR spectrum?
A band near 3415 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 3415 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) | 15 | 13 | 1.0 |
| Alkyl C-H | 6 | 6 | 1.0 |
| N h | 6 | 6 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Amine primary | 2 | 2 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 0.9 |
| Carbohydrate | 1 | 0 | 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 |
|---|---|---|---|
| humic acid | 3415, 1660, 1220 | Alkyl C-H, 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 3415 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
“The FTIR spectroscopy ofthe mixture of humic acid and 3415cm-1 linked to OH stretching of OH groups and at sulfamethoxazole showed that the absorbance at 1386cm-1becauseofOHbendingandvibrationofCOOHgroupsbecameweaker,indicatingthatCOOHgroup”
Terrestrial humic-like fluorescence peak of chromophoric dissolved organic matter as a new potential indicator tracing the antibiotics in typical polluted watershed DOI: 10.1016/j.jenvman.2018.09.013 -
Hydroxyl (O-H) confidence 1.0
“Af- (cid:3)3400 cm-1 ter the RH enters into region II, the peak at dominates the O-H stretching band and shifts to (cid:3)3415 cm-1 at 86.7% RH, while the other peaks change into”
Lu 等 - 2008 - Molecular events in deliquescence and efflorescenc DOI: 10.1063/1.2973623(cid:5) -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Mahardiani 等 - 2022 - Nanofiber Fabrication from Palm Fiber Waste for Su DOI: 10.48317/IMIST.PRSM/morjchem-v10i2.32648 -
confidence 1.0
“Stretching 3449, 1641 3415 N-H Stretching 3415, 1651”
Qin 等 - 2023 - Preparation and properties of silica solmelamine DOI: 10.1080/15685551.2022.2162280 -
Amine primary confidence 1.0
“attributed to primary amine”
Characterization of ultraviolet-photocured acrylamide based polymer DOI: 10.1063/1.4966755 -
Hydroxyl (O-H) confidence 1.0
“3 A Ag+ indicating participation of some free hydroxyl groups to cations, which results in decrease cm-1 M of electron density of the oxygen atoms because the H-O stretching band at 3415 is Ag+ slightly widened.”
Rout 等 - 2017 - A green approach to produce silver nano particles DOI: 10.1016/j.surfin.2017.03.004 -
confidence 1.0
“The FT-IR spectrum of the innovator drug was cm-1 characterized by the principal transmittance bands at 3415 and 3154 due to N-H cm-1 cm-1 (stretching), 3065 due to = C-H (aromatic stretching), 2984 and 2950 due to C-H cm-1”
Adam 等 - 2022 - Comparative Evaluation of Amlodipine Besylate Gene DOI: 10.14227/DT290422PGC2 -
confidence 1.0
“It is also Si-OH-vibration, the band at attributed to Al Siand3796cm-1and OH/Na-vibration,thebandsat3579.1to3580.5cm-1,3395.2 possiblethatthe bandsappearedat3730 3415.4cm-1,”
Ahmad 等 - 2021 - Spectroscopic Analysis for Harnessing the Quality DOI: 10.1155/2021/6629640
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