3.8. Fourier Transform Infrared (FTIR) Spectroscopy

The FTIR analysis of the samples was performed according to the methodology recently reported by Tirado-Gallegos et al. [57] using a Spectrum Two infrared spectrophotometer (Perkin Elmer Inc., Waltham, MA, USA). The procedure consisted of putting each of the samples in Ziploc™ bags (approximately 100 mg of each sample). Subsequently, each of the bags containing the sample was homogenized, and from there, a small amount was taken (≈5 mg). Samples were placed in the sample holder for ATR, and utilizing a punch, a pressure of 100 ± 1 N was exerted on the sample. The vibrational transition frequencies were reported in transmittance (%) according to the wavenumber (cm⁻¹) within the mid-infrared. An average of 34 sweeps per sample was recorded with a resolution of 4 cm⁻¹ in the region of 400 to 4000 cm⁻¹. The molecular spectral data of samples were collected and corrected with the air background and further analyzed with Spectrum Two software version 10.4. The analysis was performed in triplicate for each sample. Spectral analysis of each of the samples was selected. Therefore, the reported spectra are representative of each of the individual samples.