What absorbs at 1240 cm⁻¹ in an FTIR spectrum?
A band near 1240 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Amide | 10 | 10 | 0.95 |
| C-O single bond | 9 | 9 | 1.0 |
| Phosphate (PO4) | 5 | 4 | 0.9 |
| C n single bond | 3 | 2 | 1.0 |
| Lignin | 2 | 2 | 0.7 |
| N h | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 0.9 |
| Carbohydrate | 1 | 1 | 0.9 |
| Ammonium | 1 | 1 | 0.8 |
| Protein | 1 | 1 | 0.6 |
| Lipid | 1 | 1 | 0.6 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
confidence 1.0
“A peak around 1240 P-- RS4 microcapsules enriched extrudates which is characteristic of O P0 P5 P10 P15 P20 bonds (Shalviri et al., 2010) in RS4.”
Ashwar 等 - 2021 - Encapsulating probiotics in novel resistant starch DOI: 10.1016/j.lwt.2020.110839 -
C n single bond confidence 1.0
“Attributed to C-N stretching mode.”
Abdolahi 等 - 2012 - Synthesis of Uniform Polyaniline Nanofibers throug DOI: 10.3390/ma5081487 -
C-O single bond confidence 1.0
“Explicit assignment in text”
Gregorio 等 - 2017 - Analysis of human bodily fluids on superabsorbent DOI: 10.1016/j.talanta.2016.10.061 -
N h confidence 1.0
“N-H bending.”
Perez-Puyana 等 - 2019 - Assessment of the denaturation of collagen protein DOI: 10.1515/hsz-2019-0206 -
Amide confidence 0.95
“Explicit assignment: 'amide III bands found at around 1240'”
Manesa 等 - 2020 - Profiling of Silk Sericin from Cocoons of Three So DOI: 10.3390/ma13245706 -
confidence 0.95
“Explicit assignment: 'DNA phosphate groups (1240 ... cm-1)'”
Zlotnikov 等 - 2023 - Application Prospects of FTIR Spectroscopy and CLS DOI: 10.3390/diagnostics13040698 -
C-O single bond confidence 0.9
“Text: 'vibration of ketone C-OH at 1240'.”
Fito 等 - 2023 - Magnetite-impregnated biochar of parthenium hyster DOI: 10.1007/s13201-023-01880-y -
Phosphate (PO4) confidence 0.9
“Text: '1240cm-1(PO2 asymmetric stretching)'”
Routh 等 - 2009 - Self assembly of poly(o-methoxy aniline) with RNA DOI: 10.1016/j.bpc.2009.05.004
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