What absorbs at 1202 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1202 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 1202 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

• Amide confidence 1.0

  “= = Statistically significant differences were found between the OA groups (group 1 early OA, group 2 inter- = mediate OA and group 3 severe OA) in all univariate parameters (amide I region, carbohydrate region, collagen cm-1) integrity and”

  Imaging of Osteoarthritic Human Articular Cartilage using Fourier Transform Infrared Microspectroscopy Combined with Multivariate and Univariate Analysis DOI: 10.1038/srep30008
• Amide confidence 1.0

  “These peaks are assigned to amide III analysis method has to be validated against current biochemical cm(cid:2)1), collagen23 (1202 CH2 side chain vibrations of vibration of gold standards before it can fully replace traditional techniques.”

  Rieppo 等 - 2012 - Application of second derivative spectroscopy for DOI: 10.1016/j.joca.2012.01.010
• Phosphate (PO4) confidence 1.0

  “1654, and 1602 and within the phosphate band at 1202 and 1136 Here, the amide I subbands were set as targets for the detection of non-enzymatic cross-links with FTIR.”

  Assessment of collagen quality associated with non-enzymatic cross-links in human bone using Fourier-transform infrared imaging DOI: 10.1016/j.bone.2017.01.015.
• Amide confidence 1.0

  “SO3(cid:0) asymmetric stretching (Amide III) 1202 1200 1203* 1203 1201 CH2 wagging from glycine Table 2 backbone and from proline”

  Organic biopolymers of venus clams: Collagen-related matrix in the bivalve shells with crossed-lamellar ultrastructure DOI: 10.1016/j.bbrep.2021.100939
• Ester confidence 1.0

  “appears at 600 The bands at 1710, 1440, 1343, and 1202 cm-1 in the complex are associated with the ester group in”

  Analysis of Iron Complexes of Tannic Acid and Other Related Polyphenols as Revealed by Spectroscopic Techniques: Implications in the Identification and Characterization of Iron Gall Inks in Historical Manuscripts DOI: 10.1021/acsomega.2c01679
• confidence 1.0

  “Peaks in the 1150-550 The two bands at 1202 cm-1 and 1238 cm-1 arise from the A mode of νas S-O and νs S-O and the E cm-1 region are mainly the absorption bands of the clinker phases [59].”

  Liu 等 - 2020 - Study of the Air-Entraining Behavior Based on the DOI: 10.3390/ma13163514
• Acetate confidence 1.0

  “The centroid spectrum corresponding to fibrosis tissue was characterized by absorbance peaks related to vibrational modes of collagen as evidenced by the peaks at 1174 cm-1 (C-O stretching) [34], 1202 cm-1, 1230 cm-1, 1278 cm-1, 1304 cm-1 (”

  Moreau 等 - 2020 - Analysis of Hepatic Fibrosis Characteristics in Ci DOI: 10.3390/molecules25184092
• Acetate confidence 1.0

  “This is not surprising, bearing in mind the already reported small affinity of the Cu-Chl complex for self-agregation.33 However, two new bands emerged in the C-O stretching region, at 1202.3 cm-1 (weak) and 1118.8 (strong) - Table I.”

  Petrovic 等 - 2006 - In vitro complexes of copper and zinc with chlorop DOI: 10.2298/JSC0605501P