FTIR – Fourier Transform Infrared Spectroscopy

How FTIR works

FTIR is an analytical technique that uses the method of absorbance spectroscopy to identify chemical compounds and functional groups. Some methods of absorbance spectroscopy will only shine monochromatic light, or light of a narrow band of wavelengths, at a sample to see how much it will absorb. FTIR works a bit different – instead of shining a beam of light with a narrow range of wavelengths at the sample, it shines a beam of light that contains many different frequencies. The instrument then sees how much light was absorbed at each frequency, and from this the chemical can be characterized.

Chemicals and materials that are made of different components will have their own unique FTIR signatures. At the molecular level, functional groups and chemical structures have different rotational and vibrational movements. These functional groups will absorb light a different frequencies and intensities. For example, carboxylic acids will have a very sharp and deep peak around 1700 cm^-1 whereas alcohols will have a very broad peak that will stretch from about 3500 cm^-1 to about 3000 cm^-1. Some functional groups have very characteristic peaks that can quickly identify what the compound is, while other chemicals may take more thorough analysis into each region of the spectra for identification.

Depending on what is present in the sample, some functional groups can push and pull on different groups in the compound, causing the spectra to slightly change. In mixtures, some components can mask others, leading to more rigorous analysis and chemical identification. In some cases other analytical tools may need to be used for complex samples, but FTIR is excellent for fast and accurate identification of chemicals and materials.

About Dynalene’s FTIR instrument

Dynalene utilizes a Perkin Elmer Spectrum 100 coupled with the Spectrum Spotlight 200 Microscope to perform FT-IR analysis on a wide range of consumer goods including; plastics, polymers, oils, fibers, medications, paints, epoxy, resins and cleansers. This allows for analysis of material defects, minor contaminate analysis and surface analysis of polymers, fibers, metals, tablets and host of other materials. Equipped with Spectrum Search Plus Software and with its Infrared Spectrum Library, Dynalene can search thousands of possible matches to your sample. It can also compare the peaks in your sample’s IR spectrum with the peaks that correspond to 896 Possible Structure Units.