FTIR Analysis (FTIR Spectroscopy)

Learn that FTIR (Fourier Transform Infrared) spectroscopy is a molecular analysis technique that measures bond absorbance in samples. The analysis can be performed in absorbance or transmittance modes and is primarily used for qualitative identification.

Examine the four main sampling techniques: potassium bromide pellets for powdered samples, thin film cassettes for solid samples, sodium chloride plates with liquid (NUJOL) for liquids, and attenuated total reflectance (ATR) with crystals for solid samples.

Gather a background spectrum with no sample present so it can be subtracted from subsequent measurements, ensuring only the actual sample is analyzed.

Place the polyethylene material sample onto the ATR crystal and tighten the clamp to secure the sample in tight contact with the crystal surface.

Run multiple scans through the spectrometer to gather a comprehensive sampling of the material's infrared absorbance signature. The instrument collects data as the IR light bounces off the sample.

Transfer the collected spectrum to the library search program and initiate a database search to identify the material by comparing the spectrum to reference libraries.

Review the library results which display the best match first followed by decreasing percentage matches. The analysis identifies the sample as high-density polyethylene based on spectral comparison.