What absorbs at 827 cm⁻¹ in an FTIR spectrum?
A band near 827 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 827 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 | 6 | 5 | 1.0 |
| Chlorine | 3 | 3 | 1.0 |
| Aromatic ring | 2 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Nitrate | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| C c single bond | 1 | 0 | 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 |
|---|---|---|---|
| chitosan | 827, 1650, 1655 | Alkyl C-H | 1 |
| PVC | 827, 834, 1195 | Alkyl C-H, Chlorine | 1 |
| PVDF | 827, 1160, 840 | Alkyl C-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 827 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
-
Hydroxyl (O-H) confidence 1.0
“The 3 cm-1, other OH deformation peak can be seen at 827 as being reported by the previous study [7].”
Synthesis and characterizations of o-nitrochitosan based biopolymer electrolyte for electrochemical devices DOI: 10.1371/journal.pone.0212066 -
confidence 1.0
“C-Cl has a stretching vibration of 827 [27-29].”
Ramadan 和 Ismail - 2022 - Tunning the Physical Properties of PVDFPVCZinc F DOI: 10.21203/rs.3.rs-935328/v1 -
Alkene (C=C) confidence 1.0
“Interestingly, the peak at 827 characteristic for the (=C-H) out-of-plane bending related to the NR double bonds was still clearly observed in the spectrum of the grafted copolymer.”
Influence of the synthesis parameters on the properties of natural rubber grafted poly-3-hydroxybutyrate (acte de congrès - 10 pages) DOI: 10.1088/1757-899X/509/1/012024 -
Alkyl C-H confidence 1.0
“The peak at 827.4 also corresponds to the C-H and is present only in the virgin membrane, which suggests its degradation after”
Barros 等 - 2020 - A three-stage chemical cleaning of ion-exchange me DOI: 10.1016/j.desal.2020.114628 -
Nitrate confidence 1.0
“This can be due to the influence of: (i) nitrate vibrations in the region 2 cm-1, cm-1 1500-1300 which also cause the appearance of the weak peak at 827 [42];”
Zirconia/Hydroxyapatite Composites Synthesized Via Sol-Gel: Influence of Hydroxyapatite Content and Heating on Their Biological Properties DOI: 10.3390/ma10070757 -
confidence 1.0
“In hydrolyzed guar derivatives, spectral peaks ranging from 827.1060 cm-1 to 852.8397 cm-1 indicated the presence of alkyl halides (C-Cl stretch) Compound Functional Group CGG PGG AHGG BHGG EHGG which were not present in CGG and PGG.”
Hydrolysis, Microstructural Profiling and Utilization of Cyamopsis tetragonoloba in Yoghurt DOI: 10.3390/fermentation9010045 -
Phosphate (PO4) confidence 1.0
“shape) * 564-604 500-650 (band shape) * 500-650 (band shape) * 564, 600 v mode, 4, of the O-P-O bond Bending peak of C-O 827 827 **”
Low-Cost Deposition of Antibacterial Ion-Substituted Hydroxyapatite Coatings onto 316L Stainless Steel for Biomedical and Dental Applications DOI: 10.3390/coatings10090880 -
Alkyl C-H confidence 1.0
“For example, the band at 831 the-planebandsobservedformonomerofthematrix-isolated cm-1 cm-1 cytosine (vide supra), show that all these bands are yielded (827 in [7]) was attributed mainly to the CH”
Rozenberg 等 - 2004 - Low temperature FTIR spectroscopy and hydrogen bon DOI: 10.1016/S1386-1425(03)00251-8
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