The FTIR analysis gives you the various functional groups that are present in the analyte such as -CO, -OH, NH e.t.c. This is usually based on the frequency of the bands. Each bond type has an expected range of frequencies where they vibrate, stretch, or bend.

FTIR (Fourier-transform infrared) analysis provides a wealth of information about the chemical composition and molecular structure of a material. It is a powerful and non-destructive technique that works by measuring the absorption of infrared light by a sample. Here's a breakdown of the key information you can get from an FTIR spectrum:

• Chemical Identification and Functional Groups: The most fundamental information from FTIR is the presence of specific chemical bonds and functional groups. Each unique bond (e.g., C-H, O-H, C=O, C≡N) vibrates at a specific frequency, which corresponds to a peak in the infrared spectrum. By analyzing the position and shape of these peaks, you can determine what functional groups are present in your sample. This is often compared to a database of known spectra to identify an unknown compound.
• "Chemical Fingerprint": The region of the spectrum below approximately 1500 cm⁻¹ is known as the "fingerprint region." This area contains a complex pattern of peaks arising from the bending and stretching of single bonds. This pattern is highly specific to a particular molecule, much like a human fingerprint, and is invaluable for confirming the identity of a compound.
• Molecular Structure: While FTIR doesn't give you the full 3D structure of a molecule, the position and intensity of peaks can provide clues about the molecular environment of a functional group. For instance, the O-H stretching band of a free alcohol will appear at a different wavenumber than an O-H group that is hydrogen-bonded to another molecule.
• Quantitative Analysis: The intensity of an absorption band is directly proportional to the concentration of the functional group responsible for that band. This allows for quantitative analysis, meaning you can determine the amount of a particular component in a mixture. This is often used to measure things like the level of a certain additive in a polymer, or the degree of oxidation in a material.
• Purity and Contamination: FTIR is an excellent tool for quality control. A change in the expected spectrum, such as the appearance of new peaks or changes in the intensity of existing ones, can indicate contamination or a change in the material's composition.
• Reaction Monitoring: With techniques like in-situ ATR-FTIR, you can monitor a chemical reaction in real-time. By observing the growth and decay of specific absorption bands, you can track the consumption of reactants and the formation of products, providing information on reaction kinetics and mechanisms.
• Material Characterization: FTIR can be used to characterize a wide range of materials, including polymers, plastics, and various organic and inorganic compounds. It can help identify degradation, such as oxidation in polymers, or determine the degree of cure in a resin.

1. Functional Group Identification

• Every type of chemical bond absorbs IR radiation at specific wavenumbers (cm⁻¹).
• Example: O–H stretch (alcohols, acids): ~3200–3600 cm⁻¹ C=O stretch (aldehydes, ketones, esters, acids, amides): ~1650–1750 cm⁻¹ C–H stretch (alkanes, alkenes, aromatics): ~2850–3100 cm⁻¹ N–H stretch (amines, amides): ~3300–3500 cm⁻¹

2. Compound Identification

• Comparing the sample’s spectrum to a library database can help identify unknown compounds (pure or mixtures).

3. Structural Information

• Presence or absence of double bonds, triple bonds, aromatic rings, etc.
• Example: A sharp band near 2100–2260 cm⁻¹ indicates a C≡C or C≡N triple bond.

4. Monitoring Chemical Reactions

• You can track the disappearance of reactant peaks and the appearance of product peaks.
• Example: Tracking esterification by the appearance of a C=O ester peak and loss of the O–H alcohol peak.

5. Detection of Impurities or Contaminants

• Extra peaks in the spectrum can reveal contamination, oxidation products, or leftover reagents.

6. Hydrogen Bonding and Intermolecular Interactions

• Peak positions can shift due to hydrogen bonding, metal–ligand coordination, or changes in environment.