What absorbs at 1225 cm⁻¹ in an FTIR spectrum?
A band near 1225 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 1225 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 |
|---|---|---|---|
| Methoxy (OCH3) | 9 | 9 | 1.0 |
| Methacrylate | 9 | 9 | 1.0 |
| C-O single bond | 9 | 9 | 1.0 |
| Acetate | 9 | 9 | 1.0 |
| Nucleic acid | 6 | 6 | 1.0 |
| Phosphate (PO4) | 6 | 5 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Phosphorus | 4 | 3 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C n single bond | 3 | 3 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Lipid | 1 | 0 | 0.9 |
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 | 1225, 1650, 1655 | Acetate, Methacrylate, C-O single bond | 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 1225 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
-
Acetate confidence 1.0
“Tables 1 and 2 cm-1was 1225 assigned to C-O-C stretching vibralists goodness of fit parameter, lattice parameter, unit”
Influence of Ho3+ substitution on structural and magnetic properties of Mg–Mn ferrites DOI: 10.1007/s10854-021-05547-9 -
Amide confidence 1.0
“They showed the characteristic adsorption bands of untreated silk at 1615 (amide I), 1510 (amide II), and 1225 cm-1 (amide III).”
Ferrero 等 - 2010 - Silk Grafting with Chitosan and Crosslinking Agent DOI: 10.1007/s12221-010-0185-7 -
confidence 1.0
“Moreover, asymmetric stretching vibrations of the external and internal structure of T-O (T = Si or cm-1 cm-1, Al) were also observed which showed by the presence of band at around 1225 and 1093 respectively [13cm-1 14].”
Effect of secondary template polarity to the properties of mesoporous ZSM-5 zeolites DOI: 10.1063/1.4991190 -
Acetate confidence 1.0
“The strong peak at 1225 was the result of C-O stretching vibration absorption.”
Li 等 - 2011 - The detection of Cypermethrin on the surface of Ap DOI: 10.4028/www.scientific.net/AMR.287-290.2991 -
confidence 1.0
“Therefore, we cm-1 strate was detected with the original (untreated) Si is covered by the speculate that the peak at 1225 Si-O substrate as the background, the thickness difference stronger stretching ((cid:238)) vibration in the spectra of”
Lu 和 Mi - 2005 - Characterization of the interfacial interaction be DOI: 10.1021/ma0486896 -
Acetate confidence 1.0
“Another characteristic vibration of saffron, attributed to the C-O stretch of cm-1 C(=O)-O in the crocin ester groups, is responsible for the band located at 1225 [48].”
Naim 等 - 2022 - ATR-FTIR spectroscopy combined with DNA barcoding DOI: 10.1016/j.vibspec.2022.103446 -
Hydroxyl (O-H) confidence 1.0
“On the other hand, the peaks observed at 1424.16 and The two other successive absorption peaks detected at 1224.67 and 1178.22 were demonstrated O-H bending of carboxylic acids and phenolic compounds.”
Facile Green Synthesis of Zinc Oxide Nanoparticles with Potential Synergistic Activity with Common Antifungal Agents against Multidrug-Resistant Candidal Strains DOI: 10.3390/cryst12060774 -
Nucleic acid confidence 1.0
“In particular, the component formations of 37 peaked at ~1225 cm-1 was related to the B-form of hydrat38 to the A-form of ed ds-DNA while the one at ~1240 cm-1 39”
Zucchiatti 等 - 2016 - Contribution of Ribonucleic Acid (RNA) to the Four DOI: 10.1021/acs.analchem.6b02744
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