Fourier Transform Infra Red spectroscopy (FTIR)

What is FTIR?

FTIR is a preferred method of infrared spectroscopy. In infrared spectroscopy, IR radiation is passing through a sample. Some of the infrared radiation is absorbed by the sample and some of it passed through (transmitted). The resulting spectrum represents the molecular absorption and transmission, creating a molecular fingerprint of the sample. Compare with the spectral library, the sample is then identified with:

- material kind
- quality or consistency
- quantity.

For more info, Please refer to Education Material from Nicolet.

Scope

The sample extract (NVR) must be analyzed by FTIR to determine the presence of silicone oil, amide slip-agent, phthalate and sometimes hydrocarbon.

Brief Procedure

An analytical blank must be run with samples. Use the solvent blank to obtain the background spectrum.

Using a Pasteur pipette, transfer the methylene chloride (or hexane) extract from the sample onto the center of the salt plate one drop at a time allowing each to evaporate until all solvent is transferred.

Obtain the background and baseline corrected spectrum.

Clean the salt plate by rinsing with methylene chloride (or hexane) between each sample.

The infrared spectrum of the residue must be interpreted to determine its chemical identification.

Typical FTIR Spectra of Silicone (Dimethyl polysiloxane)
Typical FTIR Spectra of DOP (Di-octyl phthalate)
Typical FTIR spectra of Amide

Infrared Absorption Spectroscopy

Peaks useful for the identification of functional groups are located in the shorter-wavelength region of the infrared (from about 2.5 to 8.5mm), where the positions of the maxima are only slightly affected by the carbon skeleton to which the groups are attached. Following are Some Characteristic Infrared Absorptions Peaks: