What absorbs at 3346 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3346 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 3346 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

• Hydrogen bond confidence 1.0

  “2 FTIR spectra of (a) PANI-5% ECMA, (b) PANI-10% ECMA, (c) PANI-15% ECMA, (d) PANI20% ECMA, (e) PANI-50% ECMA and (f) pure ECMA powder cm-1 composites, a broad band at 3346 is assigned to interaction ECMA/PANI by formation of hydrogen bondi”

  Synthesis of novel conducting polyaniline composites based on seaweed Enteromorpha compressa macro-alga powder DOI: 10.1007/s00289-020-03191-7
• Hydroxyl (O-H) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Radiation synthesis and characterization of super-absorbing hydrogel from natural polymers and vinyl monomer DOI: 10.1016/j.envpol.2018.07.129
• confidence 1.0

  “Moreover, the intensity of the absorption peak of N-H at 3346”

  Preparation and Characterization of Self-Colored Waterborne Polyurethane and Its Application in Eco-Friendly Manufacturing of Microfiber Synthetic Leather Base DOI: 10.3390/polym10030289
• Hydrogen bond confidence 1.0

  “4(a)], peak centered at 3346 position in about 2 h, which we believe indirectly indicates the completion of the hydrogen bonding and the microphase separation process in MDIPT1k-Ur material.”

  Time-dependent morphology development in segmented polyetherurea copolymers based on aromatic diisocyanates DOI: 10.1002/polb.21652
• confidence 1.0

  “3297 [21] (9) N-H stretching 3346 3345 3345”

  Ay 和 Aydinli - 2004 - Comparative investigation of hydrogen bonding in s DOI: 10.1016/j.optmat.2003.12.004
• Hydroxyl (O-H) confidence 1.0

  “5a, the bands at 3346 show -OH stretching of intramolecular hydrogen bonds, cm-1 indicating cellulose-I in ANFs obtained from wheat straw.”

  Bian 等 - 2021 - Crystalline Structure Analysis of All-cellulose Na DOI: 10.1007/s10570-017-1259-0
• Hydroxyl (O-H) confidence 1.0

  “cm-1 ∼3736 stretching O-H cm-1 ∼3346 stretching N-H cm-1 ∼3275 stretching O-H symmetric”

  The Role of the Preanalytical Step for Human Saliva Analysis via Vibrational Spectroscopy DOI: 10.3390/metabo13030393
• Hydroxyl (O-H) confidence 1.0

  “The νOH peak of pure ◦C cm-1) cm-1) Suc at 30 (3346 was shifted to lower wavenumbers (3314 in the presence Suc at 30 °C (3346 cm-1) was shifted to lower wavenumbers (3314 cm-1) in the presence of of LEA11, indicating the formation of additi”

  Stabilization of Dry Sucrose Glasses by Four LEA_4 Proteins from Arabidopsis thaliana DOI: 10.3390/biom11050615