What absorbs at 3271 cm⁻¹ in an FTIR spectrum?
A band near 3271 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 3271 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) | 5 | 5 | 1.0 |
| N h | 5 | 4 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Ammonium | 2 | 2 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Carbon bromine | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| N-O 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 |
|---|---|---|---|
| Chitosan | 3271, 1650, 1655 | Hydroxyl (O-H), N h | 1 |
| AgNPs | 3271, 1232, 1048 | N h, Hydroxyl (O-H) | 1 |
| cotton | 3271, 1030, 1638 | Hydroxyl (O-H) | 1 |
| silver | 3271, 1636, 1310 | N h | 1 |
| silver nanoparticles | 3271, 1636, 1631 | Hydroxyl (O-H), N h | 1 |
| gold nanoparticles | 3271, 1638, 3252 | Secondary amine, C n single bond, 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 3271 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-O bond confidence 1.0
“The peaks at 3271 (Amide A) and cm-1 1637 (Amide I) showed no shift during the whole drying (phases I and II) process of semen stain but the former one sharpens with time and rapidly declined during phase II (Figs.”
Analysis of the ex-vivo transformation of semen, saliva and urine as they dry out using ATR-FTIR spectroscopy and chemometric approach DOI: 10.1038/s41598-021-91009-5 -
N h confidence 1.0
“The FT-IR spectra of all the gels showed a band at To sum up, the combination of NMR and FT-IR supported that cm-1 3271 for the NH stretching of the amide, typical of hydrogen the NDI-1/Py-1 co-assembly is possible thanks to a cooperative c”
Bartocci 等 - 2018 - Peptide-Driven Charge-Transfer Organogels Built fr DOI: 10.1002/chem.201704487 -
Ammonium confidence 1.0
“According to literature, cm-1 the bands at 1623, 1533 and 1236 which are accompanied by bands at 3355, 3271 cm-1 and 3173 (not shown) can be assigned to deformation vibrations and stretching cm-1 vibrations of ammonia, respectively [34-37].”
Doronkin 等 - 2012 - Study of the Fast SCR-like mechanism of H-2-assi DOI: 10.1016/j.apcatb.2011.11.042 -
confidence 1.0
“FTIR analysis reveal band at 3271.14, 2111.91 and 1637.82 corresponding to -N-H, -C=C, and -C-N functional groups that are responsible for the capping and stabilization of synthesized gold nanoparticles.”
Biosynthesis, characterization and antimicrobial activity of gold nanoparticles from leaf extracts of Annona muricata DOI: 10.1007/s40097-019-0301-1 -
Ammonium confidence 1.0
“The 3271 cm-1 band corresponding to the bond of NH4+ appeared in the spectrum of CTS-ZMS after adsorption [41].”
Chitosan Modified Zeolite Molecular Sieve Particles as a Filter for Ammonium Nitrogen Removal from Water DOI: 10.3390/ijms21072383 -
confidence 1.0
“The intense broad band at 3271 metal nanoparticles in the water filter have been carried out properties.25 is due to N-H and O-H stretching mode in the linkage of due to its antibacterial and as pesticide removal”
IJN-33344-synthesis-of-silver-nanoparticles-by-using-tea-leaf-extract- DOI: 10.2147/IJN.S33344 -
Hydroxyl (O-H) confidence 1.0
“gium campanulatum Eucalyptus citriodora and A C-O 1016.61 Stretch cm-1) broad hydroxyl peak (3270.82 was detected in C-Br 575.93”
Meer 等 - 2022 - Green synthesis of silver nanoparticles from Heter DOI: 10.2306/scienceasia1513-1874.2022.039 -
Alkyl C-H confidence 1.0
“Also, a moderate peak of C-H stretch Assessment of surface morphology cm-1 (in-ring) at 1425.63 of wavenumber and a strong cm-1 peak at 3270.57 wavenumbers of O-H, H-bonded were observed.”
Inkjet printing of plasma surface–modified wool and cotton fabrics with plant-based inks DOI: 10.1007/s11356-022-20659-3
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