What absorbs at 1220 cm⁻¹ in an FTIR spectrum?
A band near 1220 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 1220 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 |
|---|---|---|---|
| Methacrylate | 21 | 19 | 1.0 |
| Acetate | 21 | 19 | 1.0 |
| Methoxy (OCH3) | 20 | 18 | 1.0 |
| C-O single bond | 20 | 18 | 1.0 |
| Amide | 9 | 8 | 1.0 |
| Alkyl C-H | 8 | 6 | 1.0 |
| Lignin | 6 | 6 | 1.0 |
| Phosphate (PO4) | 5 | 4 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Silicon-oxygen (Si-O) | 4 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C n single bond | 3 | 3 | 1.0 |
| Silicon (Si) | 3 | 2 | 1.0 |
| C c single bond | 3 | 2 | 1.0 |
| Ester | 3 | 2 | 1.0 |
| Phosphorus | 3 | 2 | 1.0 |
| Carbonyl (C=O) | 3 | 1 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Sulfate (SO4) | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| S eq o | 2 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Anhydride | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Styrene | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 0.95 |
| Methyl | 1 | 0 | 1.0 |
| Alkene (C=C) | 1 | 0 | 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 |
|---|---|---|---|
| polystyrene | 1220, 1020, 1600 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| LDPE | 1220, 1720, 1737 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| Polyaniline | 1220, 1565, 1570 | Methacrylate, Acetate | 1 |
| lignin | 1220, 1035, 1510 | Methacrylate, Acetate, C-O single bond | 1 |
| wood | 1220, 1740, 1730 | Methacrylate, Acetate, 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 1220 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
“The to 1600 acyl groups, C-O (peak at 1220 and cm-1) = bacteria used LDPE as their source of carbon and made the carbonyl groups, C O (peak near 1720 was mainly necessary changes incorporating the functional groups to modify found.”
Biodegradation of Unpretreated Low-Density Polyethylene (LDPE) by Stenotrophomonas sp. and Achromobacter sp., Isolated From Waste Dumpsite and Drilling Fluid DOI: 10.3389/fmicb.2020.603210 -
Styrene confidence 1.0
“The genband at 1220 which is attributed to a five membered eral procedure for esterification of poly(styrene maleic cyclic anhydride (Bellamy, 1975).”
Galgali 等 - 2007 - Sugar-linked biodegradable polymers Regio-specifi DOI: 10.1016/j.carbpol.2006.06.035 -
confidence 1.0
“The results of this cm-1 band at 1220 is ascribed to the disappearance of amine stretchexperiment are shown in Fig.”
Revisiting the Redox Transitions of Polyaniline. Semiquantitative Interpretation of Electrochemically Induced IR Bands DOI: 10.1016/j.jelechem.2021.115593 -
Amide confidence 1.0
“LLM confirmed rule peak-group candidate”
Dual delivery of platelet‐derived growth factor and bone morphogenetic factor‐6 on titanium surface to enhance the early period of implant osseointegration DOI: 10.1111/jre.12756 -
Ester confidence 1.0
“In addition, cm-1 samples show a peak at 1220 corresponding to the ester sulfate groups, and at 1670 due to the carbonyl group contained in D-galactose.”
Preparation and Characterization of Super-Absorbing Gel Formulated from -Carrageenan–Potato Peel Starch Blended Polymers DOI: 10.3390/polym13244308 -
Lignin confidence 1.0
“well-resolved lignin bands at 1220 and 1140 develop and 1330 They concluded that the best calibration Et in decayed Scots pine.”
Pandey 和 Pitman - 2003 - FTIR studies of the changes in wood chemistry foll DOI: 10.1016/S0964-8305(03)00052-0 -
Acetate confidence 1.0
“cm(cid:3)1 (CH rockteristics of vibration peaks at 835 and 930 electrodes.22 2 It is also noticed that the semicircular portion cm(cid:3)1 cm(cid:3)1 (C-O-C stretching), 1220 and 1250 ing), 1116 is reduced and almost disappeared for plastic”
Influence of high and low dielectric constant plasticizers on the ion transport properties of PEO: NH4HF2 polymer electrolytes DOI: 10.1177/0954008319894043 -
Water (H2O) confidence 1.0
“Deconvoluted 1120cm-1 δ(H spectral bands between 1220 and of the salted and plas2O) vibrational bands due to adsorbed water around 3800 to 3200cm-1”
Characteristics of PEMA/PVdF-HFP blend polymeric gel films incorporated with lithium triflate salt in electrochromic device DOI: 10.1016/j.ssi.2011.11.035
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