What absorbs at 1318 cm⁻¹ in an FTIR spectrum?
A band near 1318 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 1318 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 | 7 | 7 | 1.0 |
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Acetate | 5 | 5 | 1.0 |
| Hydroxyl (O-H) | 5 | 4 | 1.0 |
| Carbohydrate | 3 | 3 | 1.0 |
| S eq o | 2 | 2 | 1.0 |
| Nitrate | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Oxalate | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
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 1318 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
-
C-O single bond confidence 1.0
“(cm-1) Component Spectral band Associated vibration C-C/C-O COM 780 single bond stretching C-C/C-O 1318 single bond stretching C-O 1630 double bond stretching C-O COD 1680 double bond stretching”
High precision mapping of kidney stones using mu;IR spectroscopy to determine urinary lithogenesis DOI: 10.1002/jbio.201300201 -
Alkyl C-H confidence 1.0
“Thedetectionofbandsat1318and1163cm(cid:2)1thatattributedtoδCH2 C-O-C and asymmetric stretch vibration respectively was a proof of the presence of crystallized I cellulose (Colom et al., 2003).”
Structural characterization of Argania spinosa Moroccan wooden artifacts during natural degradation progress using infrared spectroscopy (ATR-FTIR) and X-Ray diffraction (XRD) DOI: 10.1016/j.heliyon.2019.e02477 -
S eq o confidence 1.0
“(cm(cid:3)1) Band Vibration mode Main attribution Raw material Standard b-D-glucan M26/08 M49/07 M23/08 C@O 1647 v Conjugated carbonyl 1648 1655 1655 1646 CAH das 1445 CH3, CH2 1431 1436 1431 1420 CAH ds 1379 CH3 1374 1375 1375 1377 SAO 135”
Choong 等 - 2014 - Identification of geographical origin of Lignosus DOI: 10.1016/j.molstruc.2014.04.001 -
S eq o confidence 1.0
“1374 1376 1374 1375 1377 1378 SAO 1350vas Asymmetric SO2 stretching 1318 1318 1324 1318 1310 CAOAC”
Differential identification of mushrooms sclerotia by IR macro-fingerprint method DOI: 10.1016/j.saa.2015.07.054 -
Ester confidence 1.0
“cm-1 absence of a band at 1415 present in WSP and CSP, spectra indicate that it is 320 cm-1 either overlapped with a strong band at 1318 or due to the absence of O-acetyl321 ester group.”
Lefsih 等 - 2016 - Extraction, characterization and gelling behavior DOI: 10.1016/j.ijbiomac.2015.10.046 -
Alkyl C-H confidence 1.0
“HPβCD spectra gave peaks at 1080.12 (C-O-C stretch), 2910 cm-1 showed a peak at 3251 (for broad OH carboxylic), 3067 (for NH guanidine), cm-1 cm-1 cm-1 2860 (CH stretch), 1318 (CN stretch), and 1563 (presence of amide).”
Awais 等 - 2023 - Enhanced Solubility and Stability of Aripiprazole DOI: 10.3390/molecules28093860 -
Alkyl C-H confidence 1.0
“cm-1 stretching) present in hemicellulose composent, 1639 (frequency of deformation cm-1 cm-1 vibration of CH and CH groups are located), 1371 (C-H band),1318 (CH 2 cm-1 bending mode), 1281 (C-O stretching mode of ester group) stretch of th”
Boudjema 等 - 2020 - Green composites based on Atriplex halimus fibers DOI: 10.1515/polyeng-2020-0068 -
Carbohydrate confidence 1.0
“β-(1-4)-glycosidic cellulose peaks (1318 and v asC-O-C bridge of linkage: 1158 cm-1, The relative observed differences were manifested in the profiles of 3700-3000”
Impact of Natural Degradation on the Aged Lignocellulose Fibers of Moroccan Cedar Softwood: Structural Elucidation by Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD) DOI: 10.3390/fermentation8120698
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