What absorbs at 3423 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3423 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 3423 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

• Alkyl C-H confidence 1.0

  “Characteristic peaks of O-H cm-1, cm-1 stretching at 3423 C-H stretching of the CH groups at 2920 and C-O-C stretching at”

  Niaz 等 - 2020 - Alginate-caseinate based pH-responsive nano-coacer DOI: 10.1016/j.ijbiomac.2019.11.177
• confidence 1.0

  “The peak at 3423 was associated with N-H bending (Tejoset al.2004;”

  Biodegradation of Methylene Blue as an Evidence of Synthetic Dyes Mineralization during Textile Effluent Biotreatment by Acinetobacter pittii DOI: 10.1007/s40710-020-00443-6
• Hydroxyl (O-H) confidence 1.0

  “The vibrational peak around 3423 is assigned to O-H and N-H”

  Oladipo 等 - 2020 - Characterization and biomedical application of phy DOI: 10.1088/1757-899X/805/1/012021
• Acetate confidence 1.0

  “In the case of the GT, there were peaks of -NH stretching of a secondary amide at 3450 and cm-1, cm-1, 3423 of C=O stretching at 1680 and 1640 of -NH bending between cm-1,”

  Green robust pH–temperature-sensitive maleated poly(vinyl alcohol)-g-gelatin for encapsulated capsaicin DOI: 10.1007/s00289-016-1609-3
• Hydroxyl (O-H) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Synthesis and Characterization of Mesoporous Silica Functionalized with Calix[4]arene Derivatives DOI: 10.3390/ijms131013726
• Hydroxyl (O-H) confidence 1.0

  “cm-1 Regarding the cerium ions spectrum, a strong, broad peak with a frequency of 3423 is related to the (O-H) stretching vibration of the water molecules, with a bending vibration cm-1 at about 1630 [16].”

  Enhanced Coating Protection of C-Steel Using Polystyrene Clay Nanocomposite Impregnated with Inhibitors DOI: 10.3390/polym15020372
• Hydroxyl (O-H) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Baranitharan 等 - 2022 - Fabrication of Silver Nanoparticles Using Fimbrist DOI: 10.1155/2022/4083663
• Hydroxyl (O-H) confidence 1.0

  “In the LO spectrum, absorption peaks cm-1, were absent within the wavenumber range of 3200-3600 cm-1, which indicates the absence of OH were absent within the wavenumber range of 3200-3600 which indicates the absence of OH groups, while the”

  Synthesis of Linseed Oil-Based Waterborne Urethane Oil Wood Coatings DOI: 10.3390/polym10111235