What absorbs at 2019 cm⁻¹ in an FTIR spectrum?
A band near 2019 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 2019 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 |
|---|---|---|---|
| Methacrylate | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Phosphate (PO4) | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Nitrile | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Carbon dioxide | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| S eq o | 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 |
|---|---|---|---|
| calcium phosphate | 2019, 1070, 1149 | C-O single bond, Methacrylate | 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 2019 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
-
Phosphate (PO4) confidence 1.0
“Finally, the P-O (H) group presents a band at Materials 2019, 12, x FOR PEER REVIEW 6 of 21 cm-1 42-”
Development of Composite Scaffolds Based on Cerium Doped-Hydroxyapatite and Natural Gums—Biological and Mechanical Properties DOI: 10.3390/ma12152389 -
confidence 1.0
“ao, Moraes, Souza, Carciofi, Laurindo, of 1800 to 800 was used for PLSR analysis since the band is re2019) were found to produce fruit leather with high quality in sensory ported to greatly correlated with functional groups (Baum et al., 20”
Chemical versus infrared spectroscopic measurements of quality attributes of sun or oven dried fruit leathers from apple, plum and apple-plum mixture DOI: 10.1016/j.lwt.2021.112420 -
S eq o confidence 1.0
“Influence of HCl, KOH and acetolysis cm-1 Meanwhile, considering that the peak around 1,150 was also treatments on sporopollenin correlated with S=O stretch vibrations (Oh and Baiz, 2019), the”
Influence of common palynological extraction treatments on ultraviolet absorbing compounds (UACs) in sub-fossil pollen and spores observed in FTIR spectra DOI: 10.3389/fevo.2023.1096099 -
confidence 1.0
“There cm-1 was also slight shift of peaks to a higher wavenumber at 1065 after Cu and Fe impregnation on ZSM-5 and HZSM-5 in the absorption band ascribed to internal asymmetric stretch of extremely Catalysts 2019, 9, x FOR PEER REVIEW”
Hydroprocessing of Oleic Acid for Production of Jet-Fuel Range Hydrocarbons over Cu and FeCu Catalysts DOI: 10.3390/catal9121051 -
Acetate confidence 1.0
“stretching 1371 C-H bending, stretching (Shi et al., 2019) 1325 C=O stretching of syringyl units”
Bryant 等 - 2023 - Cell wall response of field grown Populus to Septo DOI: 10.3389/fpls.2023.1089011 -
Acetate confidence 1.0
“The band at 1416.39 cm-1 is assigned to symmetric C-O cm-1 Molecules2019,24,617 7of12 stretching vibrations [20].”
Efficient Degradation of High-Molecular-Weight Hyaluronic Acid by a Combination of Ultrasound, Hydrogen Peroxide, and Copper Ion DOI: 10.3390/molecules24030617 -
C-O single bond confidence 1.0
“A noteworthy observation is the degradation of the polymeric side chain which is apparent from decrease of the absorption at 1240 cm-1 attributed to the asymmetric stretching vibration C-O-C Coatings2019,9,121 6of13”
Evaluation of the Impacts of Four Weathering Methods on Two Acrylic Paints: Showcasing Distinctions and Particularities DOI: 10.3390/coatings9020121 -
C c single bond confidence 1.0
“Due to the simpler liking point between the Downloaded propyl chain and the aryl-sulfonic moieties, in this spectrum, the low frequency region appears poorer in signals, with a cm-1, sharp band centred at 1500 related to the C-C stretching”
Erigoni 等 - 2019 - Acid properties of organosiliceous hybrid material DOI: 10.1039/C9CY01609K.
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