What absorbs at 3403 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3403 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 3403 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) confidence 1.0

  “4 (c), a broad absorption peak of O-H stretching at 3403 has been cm-1.”

  Solid polymer electrolyte production from 2-hydroxyethyl cellulose: Effect of NH4NO3 composition on its structural properties DOI: 10.1016/j.carbpol.2017.02.033
• confidence 1.0

  “cm-1), with a stretch of 0.01 AU occurring only at 3403 cm-1, thus indicating a loss of H 2O due to neat castor oil, where the beginning and end absorbance values were 0.00 AU (3982 Consequently, an increase in water in its structure, an ex”

  Montenegro 等 - 2023 - Enzymatic and Synthetic Routes of Castor Oil Epoxi DOI: 10.3390/polym15112477
• Hydroxyl (O-H) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Przybylski 等 - 2008 - ESI MS, spectroscopic and semiempirical characteri DOI: 10.1016/j.molstruc.2007.07.039
• Hydroxyl (O-H) confidence 1.0

  “P-ISSN: 2320-5148 cm-1 The peak at 3403.16 arises due to the O-H GC-MS Analysis: GC-MS chromatogram for”

  Raubbin 等 - 2020 - HPLC, FTIR AND GC-MS ANALYSIS OF ETHYL ACETATE EXT DOI: 10.13040/IJPSR.0975-8232.11(8).3953-59
• confidence 1.0

  “- 1.5 sion4 1.48 N-H(cid:5)(cid:5)(cid:5)N stretching 3358 139 N-H stretching 3403”

  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

  “Loading of Flavonoid into Magnetite MNPs The FTIR spectrum (Figure 6A,B) of quercetin detected OH group stretching at 3403 and 3328 cm-1.”

  The Fine-Tuned Release of Antioxidant from Superparamagnetic Nanocarriers under the Combination of Stationary and Alternating Magnetic Fields DOI: 10.3390/antiox10081212
• Hydroxyl (O-H) confidence 0.95

  “Explicit assignment: gypsum band at ≈3403 cm-1 (ν OH)”

  Chemometrics approach to FT-IR hyperspectral imaging analysis of degradation products in artwork cross-section DOI: 10.1016/j.clay.2010.10.021.
• Hydroxyl (O-H) confidence 0.95

  “Explicit assignment.”

  Zhu 等 - 2020 - Preparation and Characterization of Regenerated Ce DOI: 10.1002/marc.2004000172