What absorbs at 1624 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1624 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 1624 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)

  Reported band

  1624 cm-1

  Assignment

  Hydroxyl (O-H)

  Material / context

  polystyrene reinforced primary sludge and fly ash; Polystyrene

  Preparation and Characterization of Sound-Absorbent Based on Polystyrene Reinforced Primary Sludge and Fly Ash from Pulp Mill DOI: 10.14716/ijtech.v14i3.5131
• Carboxyl (COOH)

  Reported band

  1624 cm-1

  Assignment

  Carboxyl (COOH)

  Material / context

  Polysaccharide; xanthan sulfate; xanthan

  Kazachenko 等 - 2021 - Food Xanthan Polysaccharide Sulfation Process with DOI: 10.3390/foods10112571
• Protein beta sheet

  Reported band

  1624 cm-1

  Assignment

  Protein beta sheet

  Material / context

  protein

  Mcavan 等 - 2020 - Quantification of protein glycation using vibratio DOI: 10.1039/c9an02318f
• Hydroxyl (O-H)

  Reported band

  1624 cm-1

  Assignment

  Hydroxyl (O-H)

  Material / context

  Ni-doped ZnO; Mn-doped; Ni-doped ZnO nanoparticles

  Comparative study on dielectric and structural properties of undoped, Mn-doped, and Ni-doped ZnO nanoparticles by impedance spectroscopy analysis DOI: 10.1007/s10854-019-02517-0
• Alkyl C-H

  Reported band

  1624 cm-1

  Assignment

  Alkyl C-H

  Material / context

  C11H15N5 derivative; metformin

  A Comprehensive Approach to Derivatization: Elemental Composition, Biochemical, and In Silico Studies of Metformin Derivatives Containing Copper and Zinc Complexes DOI: 10.3390/molecules28031406
• Alkyl C-H

  Reported band

  1624 cm-1

  Assignment

  Alkyl C-H

  Material / context

  concentration of polymers on the; HPMC; Methocel

  The effect of the source and the concentration of polymers on the release of chlorhexidine from mucoadhesive buccal tablets DOI: 10.1016/j.jsps.2019.04.012
• C c single bond

  Reported band

  1624 cm-1

  Assignment

  C c single bond

  Material / context

  grape seed extract; silver nanoparticles

  The Antimicrobial Activities of Silver Nanoparticles from Aqueous Extract of Grape Seeds against Pathogenic Bacteria and Fungi DOI: 10.3390/molecules26196081