What absorbs at 3485 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3485 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 3485 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

• C-O single bond confidence 1.0

  “x = For pure PVA, four characteristic absorption bands are observed: the one at 3485 cm-1 which is assigned to vibration along the C-OH-chains bonds in PVA;”

  Fernández 等 - 2017 - DOI: 10.17230/ingciencia.13.25.6
• confidence 1.0

  “Furthermore, the cm-1 cm-1 in the typical area was attributed to the N-H stretching vibration at 3485 cm-1 [36].”

  Purification and Characterization of a Novel Calcium-Binding Heptapeptide from the Hydrolysate of Tilapia Bone with Its Osteogenic Activity DOI: 10.3390/foods11030468
• Alkene (C=C) confidence 1.0

  “The characteristic cm-1 which can assign to the stretching vibrations of conjugate double bonds in aromatic ring absorption peak of hydroxyl appeared at 3485 and the peak of carbonyl splits into two peaks cm-1 cm-1 framework.”

  Effect of Phenolic Resin Oligomer Motion Ability on Energy Dissipation of Poly (Butyl Methacrylate)/Phenolic Resins Composites DOI: 10.3390/polym12020490
• Hydroxyl (O-H) confidence 1.0

  “The sharp pair bands at 3485 cm-1 Thr11814, 36, (+)/3428 (-) in MRh originate from the O-H stretch of and similar bands at 3485 in MG and cm-1 (+)/3432 (-) 3486 in MR are expected because of the O-H stretches of the corresponding Ser residu”

  Spectral Tuning Mechanism of Primate Blue-sensitive Visual Pigment Elucidated by FTIR Spectroscopy DOI: 10.1038/s41598-017-05177-4
• Amide confidence 1.0

  “In the spectrum of PMA (B) in Figure 2, sponded to C=O stretching (amide I), N-H bending (amide II), and C-N stretching (amcm-1 the characteristic absorption bands appeared at 3485, 2930, and 2890 due to -OH”

  Sathya Seeli 等 - 2023 - Zinc Oxide-Incorporated Chitosan-Poly(methacrylic DOI: 10.3390/jfb14040228
• Alkene (C=C) confidence 0.9

  “Explicit assignment: 'C=C from DiEP1 and DiEP2 is observable at 3485'”

  New Eco-Friendly Synthesized Thermosets from Isoeugenol-Based Epoxy Resins DOI: 10.3390/polym12010229