What absorbs at 3215 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3215 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.

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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 3215 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.

이 할당의 배경이 되는 문헌

• Ammonium 신뢰도 1.0

  “LLM confirmed rule peak-group candidate”

  Yu 等 - 2018 - Fast screening compositions of PM2.5 by ATR-FTIR DOI: 10.1016/j.jes.2017.11.021
• Water (H2O) 신뢰도 1.0

  “cm-1 For the reaction time below 90 s, Agr/GE-co-MA/AA hydrogel shows lower % swelling, which can The FTIR interpretation of GE presented peaks around 3215.2, 3361.2, and 3443.2 2◦ cm-1, be ascribed to insufficient cross-linking, resulting”

  Development of Biodegradable Agar-Agar/Gelatin-Based Superabsorbent Hydrogel as an Efficient Moisture-Retaining Agent DOI: 10.3390/biom10060939
• 신뢰도 1.0

  “the amine groups whose peaks occur at 3215 and 3068 Moreover, the new amido bonds' vibrations of C=O and the bending vibrations of N-H, indicate the presence of ADH in the modified cm-1 cm-1, C=O characteristic peaks at 1699 and 1560 corres”

  Kowalczuk - 2020 - FTIR Characterization of the Development of Antimi DOI: 10.3390/coatings10090818
• Water (H2O) 신뢰도 1.0

  “The reason for outlining the fifth peak cm-1 is the in-plane bending of water at the wavelength 1650 and Forthedeconvolutionofthespectra,OriginPro2017b9.4.0.220 the overtone of which is in Fermi resonance with the OH vibration (OriginLab Co”

  Laurson 等 - 2020 - The deconvolution of FTIR-ATR spectra to five Gaus DOI: 10.1063/5.0011700
• Hydroxyl (O-H) 신뢰도 0.9

  “OH elongation for choline chloride at 3215 cm-1.”

  Elaboration and Characterization of Natural Deep Eutectic Solvents (NADESs): Application in the Extraction of Phenolic Compounds from pitaya DOI: 10.3390/molecules27238310