What absorbs at 1654 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1654 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

Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.

Possible materials

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 1654 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

• Alkene (C=C) confidence 1.0

  “In addition, the bands at 3007 based cm(cid:0) cm(cid:0) Calibration (C-- 1 1 (=C-H asymmetric stretching), 1654 C stretching) 1438 cm(cid:0) (C-- 1 =C-H H scissoring deformation), 1258 (cis deformation), and”

  Comparison and chemical structure-related basis of species discrimination of animal fats by Raman spectroscopy using near-infrared and visible excitation lasers DOI: 10.1016/j.lwt.2020.110105
• Lipid confidence 1.0

  “194 cm-1 cm-1 Therefore, the peak ratios of 1654/1742 and of 1654/1438 in Raman spectra 195 were positively related to the total degree of unsaturation of lipid, the values of which 196 are listed in Table 1 including peak intensities and p”

  Gao 等 - 2021 - Complementarity of FT-IR and Raman spectroscopies DOI: 10.1016/j.foodchem.2020.128754
• Amide confidence 1.0

  “placenta, from in figure 6, after eight weeks of growth, shows splitting into three bands, suggesting cm-1, cm-1 cm-1 α-helices occurrence of at 1654 disordered amide I band at 1644 and ß sheet at 1625”

  Gupta 等 - 2022 - In vitro cell composition identification of wood d DOI: 10.1098/rsos.201935
• confidence 1.0

  “It is characterized by a peak that cm-1 cm-1 for the amide carbonyl group and a peak at 1540 for the appears at 1654 cm-1 (Sharma bending vibration of N-H.”

  Removal of Hexavalent Chromium by Cross-Linking Chitosan and N,N’-Methylene Bis-Acrylamide DOI: 10.1007/s40710-020-00447-2
• Alkene (C=C) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Li 和 Wang - 2022 - Study on Nitrile Oxide for Low-Temperature Curing DOI: 10.3390/ma15093396
• Amide confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Composite biocompatible hydroxyapatite⠍silk fibroin coatings for medical implants obtained by Matrix Assisted Pulsed Laser Evaporation DOI: 10.1016/j.mseb.2009.10.004
• Amide confidence 1.0

  “The second-derivative spectra in the amide I region cm-1, showed a strong peak at 1654 related to the vibration due”

  Onodera 等 - 2007 - Label-free detection of protein-protein interactio DOI: 10.1021/la7022192
• Hydroxyl (O-H) confidence 1.0

  “which lead to development of envelopes with main bands at 3433 Polyols addition resulted in increase of water captured in the model systems which was cm(cid:1)1 consistent with the increased bands at 1654 (OH bending) and 3433 (OH cm(cid:1)”

  Interactions between polyols and wheat biopolymers in a bread model system fortified with inulin: A Fourier transform infrared study DOI: 10.1016/j.heliyon.2018.