What absorbs at 1428 cm⁻¹ in an FTIR spectrum?
A band near 1428 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 1428 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 | 12 | 12 | 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) | 4 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Water (H2O) | 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 |
|---|---|---|---|
| nanocomposite | 1428, 2921, 3300 | Alkyl C-H, Methacrylate, C-O single bond | 1 |
| NiO | 1428, 1006, 1450 | Alkyl C-H, C-O single bond, Methoxy (OCH3) | 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 1428 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
“as s at 323 K and further outgassing at different temperatures inside alyst 3 3 cm-1 absorption peak at 1428 is absent which is high intense The a progressive disappearance of the adsorbed NH3+ NO bands during the rectangle:”
Low-temperature selective catalytic reduction of NO with NH3 over V/ZrO2 prepared by flame-assisted spray pyrolysis: Structural and catalytic properties DOI: 10.1016/j.apcatb.2012.08.012 -
Alkyl C-H confidence 1.0
“cm-1 vibration of The sharp peak at 1428 can be assigned to the CH 2-CO cm-1, cm-1and deformation.”
Crystal Growth, Spectral, Optical, Laser damage, Photoconductivity and Dielectric Properties of Semiorganic L-cystine hydrochloride Single Crystal DOI: 10.1016/j.saa.2015.06.113 -
Alkene (C=C) confidence 1.0
“LLM confirmed rule peak-group candidate”
Hasanuddin 等 - 2020 - Physicochemical Characterization and Controlled Re DOI: 10.22146/ijc.40921 -
Alkyl C-H confidence 1.0
“The absorption while mode 16 is primarily a CH s 1 and 2), which indicates that these terminal atoms contribute cm-1) sconsists of the COO and CH vibrations peak B (1428 s to the three normal modes.”
CH Mode Mixing Determines the Band Shape of the Carboxylate Symmetric Stretch in Apo-EDTA, Ca2+–EDTA, and Mg2+–EDTA DOI: 10.1021/acs.jpca.1c03061 -
Hydroxyl (O-H) confidence 1.0
“creasing intensity in the band 1428 cm-1 and 3380 cm-1 are related to H-O-H bending and”
Pillarization of Sumatera Bentonite by Sodium-assisted As Effective Adsorbent of Anionic Surfactants Sodium Lauryl Sulphate (SLS) Waste DOI: 10.9767/bcrec.16500) -
Alkyl C-H confidence 1.0
“peak at 1427.6 cm was assigned to -CH in alkyl substituted 3 data for the Ch-PANI-NiO nanocomposite are tabulated in Table-1, -1 amide group [48] .”
Synthesis and characterization of chitosan-polyaniline-nickel(II) oxide nanocomposite DOI: 10.1016/j.molstruc.2021.130750 -
Alkyl C-H confidence 1.0
“618 cm-1 cm-1 vibrations), 1509 (C=O and C=C vibrations), 1428 (olefinic C-H bending vibrations), cm-1 cm-1 1278 (aromatic C-O stretching vibrations), 1024 (C-O-C stretching vibrations) [13].”
Ahmed 等 - 2021 - STRUCTURAL AND OPTICAL CHARACTERISTICS OF POLY(VIN DOI: 10.4314/bcse.v35i3.12 -
Aromatic ring confidence 1.0
“X-ray diffraction pattern indicates that the bulk stretching of the quinoid ring and 1428 cm-1 are the characteristic and benzenoid ring polyaniline prepared at the optimum temperature is amorphous, whereas the polyaniline which confirms th”
Preparation of Anionic Surfactant-Based One-Dimensional Nanostructured Polyaniline Fibers for HydrogenStorage Applications DOI: 10.3390/polym15071658
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