Carboxyl (COOH) — FTIR absorption peaks and assignments

Quick answer

Carboxyl (COOH) is usually assigned by looking for a recurring cluster of characteristic peaks rather than one exact textbook number. The table below shows where the literature most often places this group in FTIR, ranked by accumulated evidence.

Characteristic FTIR peaks for Carboxyl (COOH)

Showing the 30 best-supported peaks of 1245 total for Carboxyl (COOH).

Possible materials

Spectrum logic

A functional-group assignment becomes more confident when several expected bands appear together. Use this page to find the strongest-supported peaks, then confirm that the same sample exhibits a coherent pattern rather than a single isolated hit.

Real-world usage

These pages are useful for unknown material analysis, peak explanation in reports, polymer troubleshooting, and verifying whether a candidate material family is chemically plausible.

Common mistakes

• Using one functional-group page as a complete material verdict without checking the rest of the spectrum.
• Assuming the strongest band is always the most diagnostic one.
• Forgetting that processing, additives, aging, and mixtures can shift or broaden expected peaks.

Verification advice

Use DSC, GC-MS, or TGA when several material families share similar bands or when mixture effects make the FTIR assignment uncertain.

Literature behind these assignments

• 945 cm⁻¹ confidence 1.0

  “CdO cm-1, the band in the ester group at 1751 that of 1700 cm-1 CdO cm-1 On the other hand, the Acesulfame-K band at 945 does due to the stretch in carboxylic acids, and the band CdO cm-1 not overlap with any Aspartame band, but the low sig”

  Armenta 等 - 2004 - FTIR determination of aspartame and acesulfame-k i DOI: 10.1021/jf049218l
• 1735 cm⁻¹ confidence 1.0

  “The new peak appears cm-1 at 1735 which indicates the presence of a C=O bond from carboxylic acid.”

  Arizka 等 - 2019 - Synthesis and Physical Properties Characterization DOI: 10.1088/1757-899X/546/4/042004
• 1713 cm⁻¹ confidence 1.0

  “This means that the addition shows sharp absorption and low intensity at 1712.8 cm-1 of DVB is able to shift the hydroxyl bonds in blends, which indicates the presence of C=O carbonyl so that DVB makes the blends more compatible.”

  Aritonang 等 - 2019 - Grafting of Oleic Acid On Cyclic Natural Rubber Re DOI: 10.13005/ojc/350119
• 1554 cm⁻¹ confidence 1.0

  “While in cobalt stearate, the absorption peak at wave number of 1554 cm-1indicate the presence of asymmetric vibrations of carboxylate groups absorption peak at the wave numbers of 3000”

  Asriza 和 Arcana - 2015 - SYNTHESIS OF COBALT STEARATE AS OXIDANT ADDITIVE F DOI: 10.1063/1.4930711
• 1302 cm⁻¹ confidence 1.0

  “cm-1 cm-1, characteristic peaks at 1302 and 1416 which correspond to vibrational modes 3-) (COO-) of nitrate (NO and acetate ions [50,51].”

  Sol-Gel Synthesized High Entropy Metal Oxides as High-Performance Catalysts for Electrochemical Water Oxidation DOI: 10.3390/molecules27185951
• 3275 cm⁻¹ confidence 1.0

  “The two prominent peaks at 3275.13 and 1635.54 are typical of N-H bond of amines and C=C stretch of alkenes or C=O stretch of amides [42] respectively.”

  Biomedical Applications of Cocoa Bean Extract-Mediated Silver Nanoparticles as Antimicrobial, Larvicidal and Anticoagulant Agents DOI: 10.1007/s10876-016-1055-2
• 3401 cm⁻¹ confidence 1.0

  “Obvious Fourier transform infrared cm-1, cm-1, (FTIR) spectra for the GT extract were observed, showing absorption bands at 3401 1628 cm-1, and 1029 corresponding to O-H/N-H, C=O, and C-O groups, respectively.”

  Aziz 等 - 2017 - From Insulating PMMA Polymer to Conjugated Double DOI: 10.3390/polym9110626
• 1730 cm⁻¹ confidence 1.0

  “cm-1 The peak at 1730 was assigned to C=O stretching from unconjugated ketone, carbonyl, and origin63.”

  Physicochemical characterisation of barley straw treated with sodium hydroxide or urea and its digestibility and in vitro fermentability in ruminants DOI: 10.1038/s41598-022-24738-w