What absorbs at 1420 cm⁻¹ in an FTIR spectrum?
A band near 1420 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 1420 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 | 37 | 36 | 1.0 |
| Methacrylate | 19 | 17 | 1.0 |
| Acetate | 19 | 17 | 1.0 |
| Methoxy (OCH3) | 18 | 17 | 1.0 |
| Hydroxyl (O-H) | 18 | 17 | 1.0 |
| C-O single bond | 16 | 14 | 1.0 |
| Carbohydrate | 10 | 10 | 1.0 |
| Carbonate | 9 | 8 | 1.0 |
| Aromatic ring | 8 | 7 | 1.0 |
| Carboxyl (COOH) | 7 | 6 | 1.0 |
| Lignin | 6 | 6 | 1.0 |
| Methyl | 5 | 5 | 1.0 |
| Amide | 5 | 4 | 1.0 |
| Ring structure | 4 | 3 | 1.0 |
| C c single bond | 3 | 3 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| S eq o | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 1.0 |
| Fatty acid | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 0.9 |
| Metal hydroxyl | 1 | 0 | 1.0 |
| Ketone | 1 | 0 | 1.0 |
| Ester | 1 | 0 | 1.0 |
| Silicon carbon | 1 | 0 | 0.8 |
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 1420 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
-
Alkyl C-H confidence 1.0
“Only the green group cm-1 showed to have peak located at ~1420 which is assigned for C-H bending of methyl, and”
Azlah 等 - 2020 - A fast and reliable 2D-IR spectroscopic technique DOI: 10.1016/j.vibspec.2019.103014 -
Carbohydrate confidence 1.0
“1450and1400cm(cid:2)1(Guilianoetal.,2000).Thescissoringstrongpeakat cm(cid:2)1 was attributed to the cellulose I, while cellulose II and 1430 amorphous cellulose were characterized by weak peak detected at 1420 cm(cid:2)1(Songetal.,2015).On”
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 -
Amide confidence 1.0
“A second amide vibration cm-1 cm-1 appeared at 1420 (C-H stretch), and an amide peak appeared at 1370 (C-H cm-1 stretch).”
Classification and identification of Rhodobryum roseum Limpr. and its adulterants based on fourier-transform infrared spectroscopy (FTIR) and chemometrics DOI: 10.1371/journal.pone.0172359 -
Alkyl C-H confidence 1.0
“Two other 1460cm-1 1420cm-1 bands can be assigned to alkyl groups: the first between and involve bending 1379cm-1 vibration of CH and asymmetric bending vibration of CH 3, the second at is only due to 2”
Chen 等 - 2019 - Baltic amber or Burmese amber FTIR studies on amb DOI: 10.1016/j.saa.2019.117270 -
Alkyl C-H confidence 1.0
“Further, the Si\\O\\Silayer.Inparticular,theintensepeakat3696cm-1maybeascm-1 common bands at 1420 and 1360 may be assigned tentatively C\\H (\\CH_CH cribedtoin-phasesymmetricstretchingvibrationsandtheweakpeaks to in-plane bending vibrations”
Clabel 等 - 2020 - Organo-mineral associations in a Spodosol from nor DOI: 10.1016/j.geodrs.2020.e00303 -
Aromatic ring confidence 1.0
“cm-1 The band at 1460 corresponds to the asymmetric deformation of C-H bond of xylan, while cm-1 the band at 1420 corresponds to the vibration of the aromatic ring of lignin, but also to the C-H”
Esteves 等 - 2013 - CHEMICAL CHANGES OF HEAT TREATED PINE AND EUCALYPT DOI: 10.4067/S0718-221X2013005000020 -
Hydroxyl (O-H) confidence 1.0
“At 24 h (Figure 5A), in all thicknesses, nesses, the behavior is similar: a peak corresponding to the presence of OH bonds, folthe behavior is similar: a peak corresponding to the presence of OH bonds, followed cm-1, lowed by a peak corresp”
Remineralization Potential of Three Restorative Glass Ionomer Cements: An In Vitro Study DOI: 10.3390/jcm12062434 -
Aromatic ring confidence 1.0
“in Cell-II was assigned by Liang and 710 band at 1420 characteristics of aromatic rings (1604 cm(cid:1)1) cm(cid:1)1 Marchessault23 and a strong absorption at 1272 for to the CH scissoring motion, and 2”
Characterization of chemically modified wood fibers using FTIR spectroscopy for biocomposites DOI: 10.1002/app.31746
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