What absorbs at 1226 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1226 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 1226 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

  “cm-1 cm-1 Band at 1226 is due to CH wagging, C-S stretching vibration at 664 2 cm-1 confirmed the presence of S-S group.”

  Crystal Growth, Spectral, Optical, Laser damage, Photoconductivity and Dielectric Properties of Semiorganic L-cystine hydrochloride Single Crystal DOI: 10.1016/j.saa.2015.06.113
• Borate confidence 1.0

  “A weak shoulder band cm-1 centred between 1226 and 1228 corresponds to the asymmetric stretching of B-O bonds”

  Red light Emission from Europium doped Zinc Sodium Bismuth Borate Glasses DOI: 10.1016/j.physb.2017.09.113
• S eq o confidence 1.0

  “cm-1 between 1228 and 1226 are related to S=O stretching peptide bond, which are specific to amide-I (Dumas and vibration of the sulphate ester group, a common component Miller 2003).”

  In vivo prebiotic properties of Ascophyllum nodosum polysaccharide hydrolysates from lactic acid fermentation DOI: 10.1007/s10811-019-01794-w
• Phosphate (PO4) confidence 1.0

  “cm-1 After phosphorylation process, a new peak at wavelength 980 observed which related cm-1 to P-O bond [18] and intense peak at wavelength 1226 due to P=O bond in accordance”

  Synthesis, Characterization, and Performance of Graphene Oxide and Phosphorylated Graphene Oxide as Additive in Water-Based Drilling Fluids DOI: 10.1016/j.apsusc.2019.145005
• confidence 1.0

  “Same sentence as above.”

  Synthesis of ZSM5 Zeolite Particles Using Triethanol Amine as StructureDirecting Agent DOI: 10.1111/j.1551-2916.2011.05006.x
• Acetate confidence 1.0

  “cm-1 cm-1 at 1645 for C=O stretch, at 1537 for N-H amide cm-1 bending, and at 1226 for C-O stretch (Fig.”

  Owonubi 等 - 2018 - Characterization and in vitro release kinetics of DOI: 10.1007/s40090-018-0139-2
• Acetate confidence 1.0

  “cm-1 sorption peak formed at 1226 and 1051 as a result of stretching vibration of epoxide and alkoxy (C-O) group, respectively.”

  Chufa 等 - 2021 - A Novel and Simplest Green Synthesis Method of Red DOI: 10.1155/2021/6681710
• Acetate confidence 1.0

  “1372, 1323 1338 8 1233-1214 C-O stretching in S rings 1226 1221 + 9 1270-1260 G ring C-O stretching in G rings 1269 1268”

  Dong 等 - 2020 - Pyrolysis Products Distribution of Enzymatic Hydro DOI: 10.3390/catal10020187