What absorbs at 1850 cm⁻¹ in an FTIR spectrum?
A band near 1850 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 1850 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 |
|---|---|---|---|
| Carbonyl (C=O) | 7 | 5 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Anhydride | 2 | 2 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Adsorbed carbon monoxide | 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 |
|---|---|---|---|
| polyimide | 1850, 1720, 1778 | Amide, Carbonyl (C=O), Carboxyl (COOH) | 1 |
| bio-based | 1850, 1720, 1740 | Carbonyl (C=O), Amide, Carboxyl (COOH) | 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 1850 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
-
Amide confidence 1.0
“cm-1 1850 band, another absorption band of anhydride carbonyl groups, can be used to make this correction as in cm-1 C-N Eq.”
Yang 等 - 2016 - Comparison of different methods for determining th DOI: 10.1007/s10118-016-1749-9. -
Phosphate (PO4) confidence 1.0
“4 5 cm-1 bands between 1850 and 2050 corresponded to overtones of (P=O) vibrations which are 6 7”
Acidic Properties of Alkaline-Earth Phosphates Determined by an Experimental-Theoretical Approach DOI: 10.1021/acs.jpcc.9b10472 -
Carboxyl (COOH) confidence 1.0
“The region between 1850 and 1500 cm-1 is characteristic of carboxyl and carbonyl cm-1 The region between 1850 and 1500 is characteristic of carboxyl and carbonyl groups (also α-β unsaturated), i.e., oxidized species resulting from oxygen gr”
Cicogna 等 - 2022 - Surface Functionalization of Face Masks with Cold DOI: 10.3390/molecules27238632 -
confidence 1.0
“2 the aforementioned five peaks and was assigned to CO adsorbed on a single Pt atom on the terrace [27], cm-1 whereas the weak peak at 1850 was due to a bridge site between two Pt atoms on the terrace.”
High-yield synthesis of PVP-stabilized small Pt clusters by microfluidic method DOI: 10.1016/j.cattod.2011.10.008 -
Anhydride confidence 1.0
“After ring opening polymerization of Tyr-NCA, the anhydride absorptions and 1850 cm-1, characteristic of anhydride C=O stretching.”
Supramolecular Interactions Induce Unexpectedly Strong Emissions from Triphenylamine-Functionalized Polytyrosine Blended with Poly(4-vinylpyridine) DOI: 10.3390/polym9100503 -
Alkyl C-H confidence 1.0
“C-H stretching was identified at 1850 and the bands observed cm-1, cm-1, cm-1 at 1548 1615 and 1650 were typical of amide groups.”
Influence of Functional Bio-Based Coatings Including Chitin Nanofibrils or Polyphenols on Mechanical Properties ofPaper Tissues DOI: 10.3390/polym14112274 -
confidence 1.0
“The newly observed peaks at 1850 wavelength was mainly due to the presence of cm(cid:0) 1 prove the presence of a salt of copper in the treated sample [35].”
Fire retardant properties enhancement of cotton twill fabric using pumpkin ( Cucurbita maxima ) extract DOI: 10.1016/j.heliyon.2023.e14806 -
confidence 1.0
“TGA 1850 and 1790 The C-F stretching is observed in the theoretical cm-1.”
Silva 等 - 2018 - FOURIER TRANSFORM INFRARED SPECTROSCOPY, THERMOGRA DOI: 10.21577/0100-4042.20170168
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