What absorbs at 3170 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3170 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 authoritative 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 3170 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

• Secondary amine confidence 1.0

  “2 cm(cid:1)1 in CZTS samples those matched with stretching These bands are replaced by new band at 3170 vibration from the secondary amine group.”

  CZTSxSe1−x nanocrystals_ Composition dependent method of preparation, morphological characterization and cyclic voltammetry data analysis DOI: 10.1016/j.solmat.2016.06.030
• Ring structure confidence 1.0

  “The other two n-mers and the distinct peak at 3540 cm-1 tightly bound cyclic-OH tetramers at 3280 and 3170 cm-1, respectively.”

  Ketren 等 - 2019 - Investigation on Conversion Pathways in Degradativ DOI: 10.3390/en12030528
• N h confidence 1.0

  “Raman spectrum this absorption is very small and lies at 1671 The strong absorption in the 3170cm-1 3080 region arises from the NH stretching vibrations.”

  Synthesis, Molecular Structure and Spectral Properties of Quaternary Ammonium Derivatives of 1,1-Dimethyl-1,3-propylenediamine DOI: 10.1016/j.molstruc.2007.04.036
• confidence 1.0

  “Spectra of of the zinc sulfate revealed peaks at 3170 related to OH stretching, at 1640 cm-1 4the zinc sulfate revealed peaks at 3170 cm-1 related to OH stretching, at 1640 cm-1 assigned assigned to water, and at 1060 and 980 linked to SO s”

  Humic Acid Improves Zn Fertilization in Oxisols Successively Cultivated with Maize–Brachiaria DOI: 10.3390/molecules26154588
• confidence 1.0

  “First of all, the main peak in the high frequency region (at ~3170 cm, the N-H stretching”

  Pargoletti 等 - 2020 - ORR in Non-Aqueous Solvent for Li-Air Batteries T DOI: 10.3390/nano10091735
• Alkyl C-H confidence 1.0

  “The spectrum of PANI-EB (spectrum a in Figure 1a) shows the phenyl C-H stretched at 3170 cm-1.”

  Talib 等 - 2022 - Study the structural and electrical properties of DOI: 10.15251/JOR.2022.183.389
• Aromatic ring confidence 1.0

  “N-H band at 3330.38 and a peak of aromatic stretching vibrations at 3170.10 cm-1 The C=O and P=O stretching vibrations are depicted by the peaks at 1744.39 and”

  Fabrication of PEGylated Chitosan Nanoparticles Containing Tenofovir Alafenamide: Synthesis and Characterization DOI: 10.3390/molecules27238401