What absorbs at 3228 cm⁻¹ in an FTIR spectrum?
A band near 3228 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 5 cited sources
Quick answer
A band near 3228 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| N h | 1 | 1 | 0.9 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| starch | 3228, 1650, 1540 | Hydroxyl (O-H), Carbohydrate | 1 |
| sodium alginate | 3228, 1636, 1080 | Hydroxyl (O-H) | 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 3228 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
-
Hydroxyl (O-H) confidence 1.0
“Absorption peak at 3228.19 cm-1 was attributed to O-H stretch in polymeric structure of starch resulting from intramolecular cm-1 cm-1 and intermolecular hydrogen bonding.”
Singh 和 Sharanagat - 2020 - Physico-functional and structural characterization DOI: 10.1016/j.ijbiomac.2020.07.185 -
Hydroxyl (O-H) confidence 1.0
“The broad peaks around 3228 and were q q attributed to hydroxyl (-OH) groups [9] on FNS composite.”
Thabede 等 - 2021 - Magnetite Functionalized Nigella Sativa Seeds for DOI: 10.1155/2021/6655227 -
Hydroxyl (O-H) confidence 1.0
“into the SA matrix, some characteristic band changes were observed: (1) the decrease in peak intensity cm-1 at 3228 was assigned to the reduction of -OH groups, (2) the significant decrease of peak intensity cm-1, at 2915, 2847 (correspondi”
Novel Mixed Matrix Sodium Alginate–Fullerenol Membranes: Development, Characterization, and Study in Pervaporation Dehydration of Isopropanol DOI: 10.3390/polym12040864 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Hemimorphite Flotation with 1-Hydroxydodecylidene-1,1-diphosphonic Acid and Its Mechanism DOI: 10.3390/min8020038 -
N h confidence 0.9
“N-H vibration”
Comparison of Different Methods for Spongin-like Collagen Extraction from Marine Sponges (Chondrilla caribensis and Aplysina fulva): Physicochemical Properties and In Vitro Biological Analysis DOI: 10.3390/membranes11070522
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