What absorbs at 1330 cm⁻¹ in an FTIR spectrum?
A band near 1330 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
A band near 1330 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
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Alkyl C-H | 12 | 11 | 1.0 |
| C-O single bond | 7 | 7 | 1.0 |
| Methoxy (OCH3) | 6 | 6 | 1.0 |
| Methacrylate | 6 | 6 | 1.0 |
| Acetate | 6 | 6 | 1.0 |
| Hydroxyl (O-H) | 6 | 5 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Lignin | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| S eq o | 2 | 2 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| PVC | 1330, 834, 1195 | Alkyl C-H, Methoxy (OCH3), Methacrylate | 1 |
| lignin | 1330, 1035, 1510 | Alkyl C-H, Methacrylate, C-O single bond | 1 |
| wood | 1330, 1740, 1730 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 1 |
| bamboo | 1330, 1737, 1731 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 1 |
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 1330 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
“The 1330 band 1330) assigned to the CH twisting mode shifts to lower wave number, suggesting enhancement of the CH vibration 2 2 ∆ν owing to an increase of the interchain distance.”
Hiejima 等 - 2017 - Investigation of the Molecular Mechanisms of Melti DOI: 10.24517/00050382 -
N h confidence 1.0
“It isevidentthatseveralcharacteristicabsorptionbandsat3202(NH stretching), 3098, 2928, 2871 (CH stretching), 2845, 1699 (C O stretchingcyclic),1678,1492,1452(CHbending),1420,1379,1330 cm-1 were observed in the IR spectra of and 1273 (CN str”
Hsu 和 Lin - 2009 - Rapid examination of the kinetic process of intram DOI: 10.1016/j.tca.2008.12.008 -
Borate confidence 1.0
“B-O bridging b/w B 6 cm(cid:2)1 is attributed to B-O bond The band at 1330 3(cid:2) asymmetric stretching vibrations in trigonal BO units from penta, tri, and divalent, etc.”
Lakshminarayana 等 - 2019 - Borotellurite Glasses for Gamma-Ray Shielding An DOI: 10.1007/s11664-018-6810-8 -
Alkyl C-H confidence 1.0
“trans -CH wagging of PVC presenting at 964 shifted to 969 and 968 The peaks 2 cm-1 cm-1 at around 1330 and 1250 (corresponding to the C-H bending vibration and the skeletal”
Understanding Hydrothermal Dechlorination of PVC by Focusing on the Operating Conditions and Hydrochar Characteristics DOI: 10.3390/app7030256 -
Alkyl C-H confidence 1.0
“(9) for C-H deformation in cellulose and hemicellulose, velops in the band at 1230 It has been shown that cm-1 (10) for C-H vibration in cellulose and 1330=1320 the guaiacyl type (softwood lignin) absorbs near 1268 and”
Pandey 和 Pitman - 2003 - FTIR studies of the changes in wood chemistry foll DOI: 10.1016/S0964-8305(03)00052-0 -
Hydroxyl (O-H) confidence 1.0
“To consider migration and evaporation effects as well as full degraHence, it is hypothesized that these additionally appearing side peaks dation of Irganox 1330 the results were normalized by the specific cm-1) are related to the single-oxi”
Temperature dependent degradation of phenolic stabilizers and ageing behaviour of PP-R micro-specimen DOI: 10.1016/j.polymdegradstab.2023.110311 -
Acetate confidence 1.0
“The band around 1330 and 1041 cm-1 represent C O stretching.”
CMC stabilized nano silver synthesis, characterization and its antibacterial and synergistic effect with broad spectrum antibiotics DOI: 10.1016/j.carbpol.2016.11.083 -
Carbohydrate confidence 1.0
“These bands at 1330 and 1630 have been reported to correspond to the characteristic peaks of hemicellulose and lignin in bamboo respectively [19].”
Investigating the Effect of Smoke Treatment on Hygroscopic Characteristics of Bamboo by FTIR and Raman Spectroscopy DOI: 10.3390/ma15041544
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