What absorbs at 1418 cm⁻¹ in an FTIR spectrum?
A band near 1418 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 1418 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 |
|---|---|---|---|
| Alkyl C-H | 10 | 8 | 1.0 |
| Methoxy (OCH3) | 9 | 9 | 1.0 |
| Acetate | 9 | 9 | 1.0 |
| Methacrylate | 8 | 8 | 1.0 |
| C-O single bond | 7 | 6 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| C c single bond | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Methyl | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Protein | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Carbonate | 2 | 2 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Oxalate | 1 | 1 | 0.9 |
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 | 1418, 1650, 1655 | Alkyl C-H, Acetate, Methacrylate | 1 |
| NaOH | 1418, 3429, 897 | Alkyl C-H, Methoxy (OCH3), Methacrylate | 1 |
| polyaniline | 1418, 1565, 1570 | Alkyl C-H, Methacrylate, Acetate | 1 |
| copolymer | 1418, 2921, 1540 | Alkyl C-H, Methacrylate, Acetate | 1 |
| silver nanoparticles | 1418, 1636, 1631 | Alkyl C-H, Methacrylate, Acetate | 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 1418 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
-
Aromatic ring confidence 1.0
“cm-1, which indicate C C the peaks at 1535and 1487 wileyonlinelibrary.com] stretching mode in quinoid ring and benzenoid ring, cm-1 respectively,[22]peaks at 1418and at 3361 appear TABLE 1 Peak position and ((cid:1))”
Dey Sadhu 等 - 2020 - Preparation and characterization of polyanilinea DOI: 10.1002/pc.25738 -
confidence 1.0
“2 3 cm-1, cm-1, group peak at 1376 C-N axial deformation (amino group peak) at 1418 CH 2 (1-4)-glucosidic”
Removal of Hexavalent Chromium by Cross-Linking Chitosan and N,N’-Methylene Bis-Acrylamide DOI: 10.1007/s40710-020-00447-2 -
C c single bond confidence 1.0
“cm-1(broadband 3273 with high intensity), aromatic C-C the improvement in the thermal stability of the prepared S/ cm-1, cm-1, stretching at 1418 and rocking of CH at 715 GG-microencapsulate.”
Garden cress gum and maltodextrin as microencapsulation coats for entrapment of garden cress phenolic-rich extract: improved thermal stability, storage stability, antioxidant and antibacterial activities DOI: 10.1007/s10068-022-01171-3 -
Carbonyl (C=O) confidence 1.0
“A major peak at 1638 corresponds to carbonyl stretch of cm-1 quinone24, conjugate ketone or the peak at 1418 and 1364 corresponds to O-C-H, C-C-H, C-O-H bending 2 Scientific RepoRtS | | https://doi.org/10.1038/s41598-020-62895-y (2020) 10:6”
Microbial quality assessment of minimally processed pineapple using GCMS and FTIR in tandem with chemometrics DOI: 10.1038/s41598-020-62895-y -
Carbonate confidence 1.0
“FTIR analysis of TiO2NPs using ESE showed sharp peaks at 720, 870, 1047/1060, and 1410/1418 cm-1, which can be attributed to the vibrations of carbonate CO3-2 anions (Figure 6B) [58,59].”
Green Synthesis of Silver and Titanium Oxide Nanoparticles Using Tea and Eggshell Wastes, Their Characterization, and Biocompatibility Evaluation DOI: 10.3390/su151511858 -
Protein confidence 1.0
“The peaks at 1418, 875, and cm-1 perature and weight loss of the unmodified and modified 712 correspond to other proteins in the membrane.”
The Taste of Waste: The Edge of Eggshell Over Calcium Carbonate in Acrylonitrile Butadiene Rubber DOI: 10.1007/s10924-019-01530-y -
Alkyl C-H confidence 1.0
“The cm-1 cm-1 peak near 1418 is attributed to the CH bending [48].”
Enhanced Saccharification of Purple Alfalfa via Sequential Pretreatment with Acidified Ethylene Glycol and Urea/NaOH DOI: 10.3390/pr10010061 -
Chitosan confidence 1.0
“The FTIR spectra of the CTS-ZMS (red line and black line) illustrated the band at 1654 cm-1 corresponded to the -NH2 bond of the amine group while the band at 1418 cm-1 was attributed to -COObond, these two bands indicated the typical group”
Chitosan Modified Zeolite Molecular Sieve Particles as a Filter for Ammonium Nitrogen Removal from Water DOI: 10.3390/ijms21072383
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