What absorbs at 1371 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1371 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 1371 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

  “C=O stretching in conjugated aryl ketone of lignin carbonyl groups 1511 A romatic skeletal stretching 1371 Aliphatic C-H in-plane deforming and stretching Ar-O stretching in oxygen bond of benzene ring (lignin) 1268”

  Cheng 等 - 2011 - The Research on the Longitudinal Tensile Strength DOI: 10.4028/www.scientific.net/AMR.183-185.2014
• Alkyl C-H confidence 1.0

  “C-- and 1 (cis-olefins C (ester) stretching vibration), a small peak at 1651 cm(cid:0) 1 (cid:0)0.984** stretching vibration), peak at 1465 (designated to bending vibraunroasted Value, cm(cid:0) PUFAs -C-H -C-H 1 tion of (CH2)), a small pea”

  Impact of microwave roasting on physicochemical properties, maillard reaction products, antioxidant activity and oxidative stability of nigella seed (Nigella sativa L.) oil DOI: 10.1016/j.foodchem.2021.130777
• Alkyl C-H confidence 1.0

  “2 cm-1 triglycerides), sharp peak at 1745 (associated with stretching vibration of ester carbonyl cm-1 (C=O) functional groups of the triglycerides), small peak at 1651 (related to C=C cm-1 stretching vibration of cis-olefins), peak at 1465”

  Impact of infrared and dry air roasting on the oxidative stability, fatty acid composition, Maillard reaction products and other chemical properties of black cumin (Nigella sativa L.) seed oil DOI: 10.1016/j.foodchem.2019.05.140
• Alkyl C-H confidence 1.0

  “The FTIR band positions at 1371 cm-1 doping concentrations have shown thermal resistance value to 1376 indicates the -CH 2CH bonding, which fur3 of 14.64 and 16.53 K/W respectively.”

  Investigation of rheological, structural, surface, optical and thermal properties of low temperature produced silver doped ZnO thick film as thermal interface material in lighting application DOI: 10.1007/s10854-017-6773-1
• Acetate confidence 1.0

  “characteristic of C-O stretching bonds were observed (1371 and at 1010 All of these bands are related to the alginate and maltodextrin molecular structures.”

  Encapsulation of Cochleates Derived from Salmonella Infantis with Biopolymers to Develop a Potential Oral Poultry Vaccine DOI: 10.3390/polym13193426
• Hydroxyl (O-H) confidence 1.0

  “Furthermore, the OH bending vibration of the phenol group was detectable at 1396 and 1371 cm-1 in the Agrimonia eupatoria L.”

  In Situ Gel with Silver Nanoparticles Prepared Using Agrimonia eupatoria L. Shows Antibacterial Activity DOI: 10.3390/life13020573
• Alkyl C-H confidence 1.0

  “cm-1 stretching) present in hemicellulose composent, 1639 (frequency of deformation cm-1 cm-1 vibration of CH and CH groups are located), 1371 (C-H band),1318 (CH 2 cm-1 bending mode), 1281 (C-O stretching mode of ester group) stretch of th”

  Boudjema 等 - 2020 - Green composites based on Atriplex halimus fibers DOI: 10.1515/polyeng-2020-0068
• Alkyl C-H confidence 1.0

  “Yang et al., 2020) 1423 C-H deformation, CH2 stretching 1371”

  Bryant 等 - 2023 - Cell wall response of field grown Populus to Septo DOI: 10.3389/fpls.2023.1089011