What absorbs at 3528 cm⁻¹ in an FTIR spectrum?
A band near 3528 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 4 cited sources
Quick answer
A band near 3528 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 | 2 | 1.0 |
| Water (H2O) | 3 | 2 | 1.0 |
| N h | 3 | 1 | 1.0 |
| Alkene (C=C) | 2 | 1 | 1.0 |
| Alkyl C-H | 2 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
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 |
|---|---|---|---|
| cellulose acetate | 3528, 1650, 1741 | Hydroxyl (O-H) | 1 |
| alginate | 3528, 1100, 1715 | 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 3528 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
-
Acetate confidence 1.0
“- 1701 1708 1715 1721 1727 1730 C=O stretching 3528 3389 3350 3342 3328 3335 3305 3298 O-H stretching interest that would lead to the complexation between alginate alginate model and glycolic acid was optimized through ge- -COOC-O-C, -OH an”
Enhancing proton conductivity of sodium alginate doped with glycolic acid in bio-based polymer electrolytes system DOI: 10.1007/s10965-020-02142-0 -
confidence 1.0
“(cm(cid:1)1) Wavenumber Assignment groups Tacrine + 4-PyC8 PC-37 + 4-PyC8 N-H/O-H stretching 3527.98”
Multi-spectroscopic monitoring of molecular interactions between an amino acid-functionalized ionic liquid and potential anti-Alzheimer's drugs DOI: 10.1039/d0ra06323a -
Water (H2O) confidence 1.0
“The broad peaks observed near 3528 and 3396 corresponded to cm-1 the stretching vibration of crystalline water within the gypsum, while the 1620 peak 42represented the variable angle vibration of crystalline water.”
Multi-Method Analysis of Painting Materials in Murals of the North Mosque (Linqing, China) DOI: 10.3390/coatings13071298 -
Hydroxyl (O-H) confidence 1.0
“cm-1 There is a broad absorption band resonating at 3528 corresponding to the stretching vibration of the OH cm-1 groups.”
Improved anti-biofouling resistances using novel nanocelluloses/cellulose acetate extracted from rice straw based membranes for water desalination DOI: 10.1038/s41598-022-08324-8
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