What absorbs at 1543 cm⁻¹ in an FTIR spectrum?
A band near 1543 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 1543 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 |
|---|---|---|---|
| Amide | 23 | 22 | 1.0 |
| N h | 9 | 9 | 1.0 |
| Carboxyl (COOH) | 7 | 6 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Carbonyl (C=O) | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| Ketone | 3 | 3 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Protein beta sheet | 2 | 2 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| C=n | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
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 1543 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
“cm-1 Amide I and 1543 peak of Amide II for protein peak of typical protein peaks(Wang, et al., 2005).”
JOONSUK - 2019 - ATR-FTIR Analysis of Adhesives Jointing Buddhist S DOI: 10.12654/JCS.2019.35.1.02 -
Amide confidence 1.0
“vC@O 1647 Conjugated carbonyl (amide I band) 1652 1651 1644 1643 1638 1646 1546 vas NO2 (amide II band) 1543”
Differential identification of mushrooms sclerotia by IR macro-fingerprint method DOI: 10.1016/j.saa.2015.07.054 -
confidence 1.0
“cm-1, PVAM-g-GT 1 h, the showed the peak for C=O stretching at 1643 N-H cm-1, cm-1 bending at 1543 C=O and C-O stretching at 1711 and 1227 that were assigned to the presence of carboxylic groups in the chemical structure.”
Green robust pH–temperature-sensitive maleated poly(vinyl alcohol)-g-gelatin for encapsulated capsaicin DOI: 10.1007/s00289-016-1609-3 -
Carbonate confidence 1.0
“cm-1 the bands at 1370, 1457 and 1510 could be assigned to the symmetric and asymmetric the bands at 1370, 1457 and 1510 cm-1 could be assigned to the symmetric and asymmetric cm-1 stretching of monodentate carbonates, while the bands at 13”
Thermal and Plasma-Assisted CO2 Methanation over Ru/Zeolite: A Mechanistic Study Using In-Situ Operando FTIR DOI: 10.3390/catal13030481 -
Carboxyl (COOH) confidence 1.0
“In addition, in cm-1, the painting layer, there was a band at 1543 which was related to the presence of carboxylates (C=O stretching), normally related to the reaction products of drying oil and”
Removal of a Past Varnish Treatment from a 19th-Century Belgian Wall Painting by Means of a Solvent-Loaded Double Network Hydrogel DOI: 10.3390/polym13162651 -
Amide confidence 1.0
“cm-1, cm-1, Our results show that the Amide I band maxima were found at 1650 1653 cm-1, cm-1, cm-1, cm-1 and 1657 and Amide II bands maxima at 1543 1547 and 1553 for PVRm, ERMi, and PDRm, respectively, indicating differences in the secondar”
Andjelic 等 - 2023 - Characterization of Different Types of Epiretinal DOI: 10.3390/ijms24054834 -
Amide confidence 1.0
“The amide I at 1653 and the amide II cm-1 band at 1543 are well resolved.”
Baumgartner 等 - 2020 - 3D Printing for Low-Cost and Versatile Attenuated DOI: 10.1021/acs.analchem.9b04043 -
confidence 1.0
“Moreover, in the samples of 0.5ZrO 2·0.5HAp the cm-1 the BSA band at 1543 also appears, due to N-H in-plane bending of amide II [64].”
Zirconia/Hydroxyapatite Composites Synthesized Via Sol-Gel: Influence of Hydroxyapatite Content and Heating on Their Biological Properties DOI: 10.3390/ma10070757
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