Nicolet 380 thermo corporation fourier transform infrared ftir spectrometer

Infrared spectra were recorded in the 550–4000 cm⁻¹ range with a Nicolet 380 Thermo Corporation Fourier Transform Infrared (FTIR) Spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) equipped with smart Itx ATR (Attenuated Total Reflection) accessory with a diamond plate, collecting 256 scans at 4 cm⁻¹ resolution. ONMIC software was used to modify the intensity of spectra and for shifting them to obtain the normalization with respect to selected reference bands, for a better comparison of spectra profiles. The spectra were recorded onto films prepared by PLA and PS acrylic copolymer dissolved in chloroform.

Chitin and chitosan powders were crushed and homogenized using a pestle in a mortar. To perform infrared characterization, powder was transferred from the mortar to the ATR crystal using a spatula. Infrared spectra were recorded in the 550–4000 cm⁻¹ range with a Nicolet 380 Thermo Corporation Fourier Transform Infrared (FTIR) Spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) equipped with a smart Itx ATR (Attenuated Total Reflection) accessory with a diamond plate, collecting 256 scans at 2 cm⁻¹ resolutions. At least three replicates from each batch were analyzed. For each sample, the RAC ratio was calculated and correlated to the acetylation degree of the sample, and it was determined as reported by the following equation:
where A_amide is the area of the band obtained by integrating the peak at 1650 cm⁻¹ related to the CO stretching (Amide I) in the range of 1695–1618 cm⁻¹, and A_reference is the area of the reference band in the range of 1184–1024 cm⁻¹ corresponding to C-O-C stretching movements. The integrals were measured after tracing a baseline passing through the minima present in all the spectra at about 1735 cm⁻¹ and 1185 cm⁻¹. EZ OMNIC software (OMNIC 7.2, Thermo, Waltham, MA, USA) was used to elaborate the spectra and measure the integrals.

Infrared spectrum of bran was recorded in the 550–4000 cm⁻¹ range with a Nicolet 380 Thermo Corporation Fourier Transform Infrared (FTIR) Spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) equipped with Smart Itx ATR (Attenuated Total Reflection) accessory with a diamond plate, collecting 256 scans at 2 cm⁻¹ resolutions.