What absorbs at 2600 cm⁻¹ in an FTIR spectrum?
A band near 2600 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 2600 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 9 | 8 | 1.0 |
| Water (H2O) | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Thiol | 2 | 2 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Phosphate (PO4) | 2 | 1 | 1.0 |
| S s | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Adsorbed carbon monoxide | 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 |
| Sulfate (SO4) | 1 | 0 | 0.8 |
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 |
|---|---|---|---|
| AgNPs | 2600, 1232, 1048 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| polymers | 2600, 1726, 1743 | Alkyl C-H | 1 |
| coal | 2600, 1600, 3030 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| silver nanoparticles (AgNPs) | 2600, 1100, 1749 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| chitosan | 2600, 1650, 1655 | 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 2600 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
“2528cm-1 are assigned to O-D in COD The peaks at 2600 and bonded to free COOH groups (Table 5), so that OH-π hydrogen bonds bonds [31].”
Insight into the interaction between hydrogen bonds in brown coal and water DOI: 10.1016/j.fuel.2018.09.119 -
Hydrogen bond confidence 1.0
“Hence, it is undeniable that a hydrogen bond O-D cm-1.9 The broadness of this peak appeared at 2600 coal.5 exists in band is also drastically reduced after the coal samples Now, it has been well-known that hydrogen bonding alkylated.10,11 A”
Li 等 - 2003 - A new hydrogen bond in coal DOI: 10.1021/ef020169t -
Hydroxyl (O-H) confidence 1.0
“Similar changes induced by plasma treatment of the strucsmectites affected the framework region (530 and to a (4000ture of the natural zeolite, Ag-zeolite, bentonite clay, etc., have been lesser degree compared to the hydroxyl stretching re”
Dikmen 等 - 2020 - Characterization of Ag-exchanged clinoptilolite tr DOI: 10.1180/clm.2020.33 -
Acetate confidence 1.0
“cm-1, (C = O stretch in carboxylic groups at 1725 less intensive shoulder of H-bonded cm-1, cm-1) dimers at 2600 C-O stretch at 1220 and (ii) methyl vibrations (clearly visible cm-1, cm-1).”
Incorporation of Natural Blueberry, Red Grapes and Parsley Extract By-Products into the Production of Chitosan Edible Films DOI: 10.3390/polym13193388 -
Water (H2O) confidence 1.0
“2600 Corresponding positive bands of the water O-D C 11=C group in the all-trans form.”
Hanai 等 - 2021 - Light-induced difference FTIR spectroscopy of prim DOI: 10.2142/biophysico.bppb-v18.005 -
Adsorbed carbon monoxide confidence 1.0
“In all spectra the peaks for CHx (2933 cm-1), CO2 (2357 cm-1) and NH3 (968 cm-1) are significantly evident with no signs of either a carbon monoxide or CO doublet at 2100 and 2200 cm-1 or, in the PA66/BrPS (and PA66/PPBz) samples, HBr P and”
Holdsworth 等 - 2020 - Potential Synergism between Novel Metal Complexes DOI: 10.3390/polym12071543 -
Hydroxyl (O-H) confidence 1.0
“The peak in the spectra around 2600 was due to the OH”
Hydrolysis, Microstructural Profiling and Utilization of Cyamopsis tetragonoloba in Yoghurt DOI: 10.3390/fermentation9010045 -
Alkyl C-H confidence 1.0
“roseus 2900 in pure stretched and shifted to the lower side observed at 2600 cm-1 which corresponds to the presence of C-H stretching bond.”
Biogenic Synthesis of Silver Nanoparticles Using Catharanthus roseus and Its Cytotoxicity Effect on Vero Cell Lines DOI: 10.3390/molecules27196191
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