What absorbs at 1582 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1582 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 1582 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

  “Gavira and coworkers observed a medium band at 1616 and a 2 cm-1 very weak peak at 1582 in the FTIR spectrum of cytidine 3'-monophosphate (3'-CMP) and assigned them to be the ribose C-H vibrations and in-plane base vibrations, respectively.”

  Peng 等 - 2011 - Anharmonic Vibrational Modes of Nucleic Acid Bases DOI: 10.1021/ja205636h
• confidence 1.0

  “1649 C-N stretching and N-H bending vibration - - - 1582 1547 1542 of amide II”

  Sukprasert 等 - 2020 - Synchrotron FTIR Light Reveals Signal Changes of B DOI: 10.1155/2020/6149713
• Aromatic ring confidence 1.0

  “In addition, weak peaks at 1582 and 1601 in spectrum (d) are indicative of aromatic components' ring stretching.”

  Evaluation of the Composition, Thermal and Mechanical Behavior, and Color Changes of Artificially and Naturally Aged Polymers for the Conservation of Stained Glass Windows DOI: 10.3390/polym15122595
• Aromatic ring confidence 1.0

  “vibration aromatic ring 1582 (vw) 1585 (vw) skeletal [41] vibration δas (C-”

  De Sa 等 - 2021 - Tracing Poly(Vinyl Acetate) Emulsions by Infrared DOI: 10.3390/polym13213609
• Carbonyl (C=O) confidence 1.0

  “The carbonyl and benzene ring stretching vibrations are exhibited at 1660 cm-1 and 1582 cm-1, respectively.”

  Regularities of Encapsulation of Tolfenamic Acid and Some Other Non-Steroidal Anti-Inflammatory Drugs in Metal-Organic Framework Based on -Cyclodextrin DOI: 10.3390/pharmaceutics15010071
• confidence 1.0

  “The band at 1582 attributed to the bending vibration of N-H group has been confirmed in the investigation.”

  Haniffa 等 - 2019 - Synergistic effect of (3-Aminopropyl)Trimethoxysil DOI: 10.1016/j.polymdegradstab.2018.11.009
• C c single bond confidence 1.0

  “FTIR: stretching, 1582.21 and 1506.57 for for 2 cm-1 cm-1 C- -C-H -NO stretching, 1334.50 stretching, 3093.43 for aromatic stretching, for aromatic stretching, 2”

  Manjare 等 - 2023 - Microwave-Assisted Rapid and Green Synthesis of Sc DOI: 10.1021/acsomega.2c05187
• Alkyl C-H confidence 1.0

  “Also, the peak at 1582 corresponding to bending vibrations of C-H, faded away, indicating that the N-H bonds on cotton-g-PSMA were converted to N-Cl bonds during chlorination .”

  Peng 等 - 2021 - Grafted antimicrobial cotton fabrics with N-halami DOI: 10.21203/rs.3.rs-261084/v1