What absorbs at 2889 cm⁻¹ in an FTIR spectrum?
A band near 2889 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 2889 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 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Carbohydrate | 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 |
|---|---|---|---|
| polyethylene | 2889, 1737, 1720 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| PVA | 2889, 1660, 2930 | Alkyl C-H, Hydroxyl (O-H), Amide | 1 |
| PEG | 2889, 1650, 1342 | Alkyl C-H, 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 2889 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
“LLM confirmed rule peak-group candidate”
Burhan 等 - 2020 - Preparation of Cyperus diffusus Vahl cellulose-pol DOI: 10.1088/1757-899X/833/1/012063 -
Alkyl C-H confidence 1.0
“FTIR peak cm-1 cm-1 centring at 3450 represents OH stretching and peak appearing at 2889 was due to C-H”
Niaz 等 - 2020 - Alginate-caseinate based pH-responsive nano-coacer DOI: 10.1016/j.ijbiomac.2019.11.177 -
Alkyl C-H confidence 1.0
“cm-1, Figure 6 shows that the C-H aliphatic stretching band for PEO appears at 2889 and this peak Figure 6 shows that the C-H aliphatic stretching band for PEO appears at 2889 cm-1, and this different was shifted to lower wavenumbers upon b”
Preparation and Composition Optimization of PEO:MC Polymer Blend Films to Enhance Electrical Conductivity DOI: 10.3390/polym11050853 -
Alkyl C-H confidence 1.0
“For the spectrum of PEG, the spectral band appeared at 3463 for cm-1 cm-1 O-H stretching vibrations, 2889 for C-H stretching vibrations, and 1469 and 1342 for C-H cm-1 bending vibrations.”
Green Synthesis and Characterization of Silver/Chitosan/Polyethylene Glycol Nanocomposites DOI: 10.3390/ijms12084872 -
Alkyl C-H confidence 1.0
“The peak at 2889 is cm(cid:0) 1 C-H attributed to the medium stretching alkane confirming the presence of polysaccharides [41].”
Development and characterization of natural sourced bioplastic for food packaging applications DOI: 10.1016/j.heliyon.2023.e13538 -
Amide confidence 1.0
“FTIR bands at 2945 and 2889 cm-1) peptide bond bands (amide I ~1640 and amide II ~1540 were not detected, suggesting that proteins are not related to mineral synthesis or their stabilization.”
Fragoso 等 - 2010 - Characterization of the CaCO3 biomineral in corall DOI: 10.7773/cm.v36i1.1606 -
Alkyl C-H confidence 1.0
“The HSA NPs ◦C, 2889 cm-1 is related to the C-H bond, 1728 cm-1 corresponds to the C=O bond, 1462 cm-1 showed a characteristic endothermic peak at around 120 which probably corresponds indicates C=C, 1365 cm-1 is related to CH2 and C=C, and”
Human Serum Albumin Nanoparticles: Synthesis, Optimization and Immobilization with Antituberculosis Drugs DOI: 10.3390/polym15132774 -
Alkyl C-H confidence 1.0
“cm-1 FTIR data of pure PL is characterized by principal absorption peaks at 2889 (C-H stretching cm-1”
Solid-state characterization of triamcinolone acetonide nanosuspensiones by X-ray spectroscopy, ATR Fourier transforms infrared spectroscopy and differential scanning calorimetry analysis DOI: 10.1016/j.ijpharm.2017.03.082
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