How can you identify CO2 from FTIR?

Quick answer

CO2 is usually reported with a recurring pattern of peaks and functional-group evidence. The most useful approach is to cross-check at least two characteristic peaks before treating it as a match, then verify whether the full spectrum still fits the same material family.

Peak interpretation

Possible materials / groups

Spectrum logic

The logic here is evidence aggregation: repeated literature mentions of CO2, repeated peak positions, and repeated functional-group associations. A strong material hypothesis should still be supported by multiple peaks that agree with each other, not by one headline band alone.

Real-world usage

This page is designed for polymer identification, incoming-material QC, unknown plastic analysis, recycled-content review, and literature-backed interpretation of reference spectra.

Common mistakes

• Calling a material match too early because one famous peak is present.
• Ignoring sample prep, fillers, oxidation, water, or additives that can change the apparent pattern.
• Using literature evidence without checking whether your own sampling mode and spectrum quality are comparable.

Verification advice

Use DSC, GC-MS, or TGA to validate the material hypothesis when the peak pattern is ambiguous or mixed.

Literature behind this page

• confidence 0.9

  CO2

  In situ gas monitoring in clay rocks: mathematical developments for CO2 and CH4 partial pressure determination under non-controlled pressure conditions using FT-IR spectrometry DOI: 10.1039/c0ay00622j
• confidence 0.9

  CO2

  Lorentz half-width, pressure-induced shift and speed-dependent coefficients in oxygen-broadened CO2 bands at 6227 and 6348 cm−1 using a constrained multispectrum analysis DOI: 10.1016/j.jqsrt.2010.06.003
• confidence 0.9

  CO2

  Sorption of CO2, CH4 and Their Mixtures in Amorphous Poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) DOI: 10.3390/polym15051144
• confidence 0.9

  CO2

  Intercomparison of in situ NDIR and column FTIR measurements of CO ₂ at Jungfraujoch DOI: 10.5194/acp-16-9935-2016
• confidence 0.8

  CO2

  On the CO2 sorption and swelling of elastomers by supercritical CO2 as studied by in situ high pressure FTIR microscopy DOI: 10.1016/j.supflu.2017.09.003
• confidence 0.8

  CO2

  Eigenmann 等 - 2006 - Influence of measuring conditions on the quantific DOI: 10.3929/ethz-b-000000584
• confidence 0.8

  CO2

  Absolute accuracy and sensitivity analysis of OP-FTIR retrievals of CO ₂ , CH ₄ and CO over concentrations representative of "clean air" and "polluted plumes" DOI: 10.5194/amt-4-97-2011
• confidence 0.7

  CO2

  Carboxylation of Toluene by CO₂Generating<i>p</i>-Toluic Acid: A Kinetic Look DOI: 10.1021/ie300014z
• confidence 0.7

  CO2

  Using XCO ₂ retrievals for assessing the long-term consistency of NDACC/FTIR data sets DOI: 10.5194/amt-8-1555-2015
• confidence 0.7

  CO2

  Carbon isotope ratio analysis in CO2 based on Fourier transform infrared spectroscopy DOI: 10.7498/aps.62.030202