Nicolet iz 10 ftir instrument

Characterization of the compounds was performed using ¹H-NMR, COSY-NMR and IR spectroscopy. ¹H-NMR spectra were recorded using a Bruker Avance 400 instrument operating at 400.13 MHz at 300 K. NMR samples were prepared in D₂O at concentrations of 10–15 mg/mL. The N-acetyl peak (2.08 ppm) was used as the internal reference in all spectra. FT-IR measurements were performed with a Nicolet iZ10 FT-IR instrument (Thermo Scientific Corporation, Bartlesville, OK, USA). Samples were placed over a diamond crystal and the spectrum was recorded using OMNIC 7 software. Each spectrum was collected in transmittance using 32 scans, resolution of 4 and data spacing of 0.482 cm⁻¹.
Equivalent quantities of reagents were calculated using one glucosamine unit. The degree of substitution (DS) for the N,N,N-trimethyl chitosan derivative was evaluated on the basis of the integral values in ¹H NMR. The following equations were used for calculating the degree of acetylation (DA) and the degree of substitution (DS) for the chitosan derivatives:
(1)

Degree of acetylation, DA=[∫HAc∫H2−H6×63]×100 (1)

(2)

DS for N,N,N-trimethylation, DSTRI=[∫N−CH3∫H2−H6×69]×100 (2)

where H2 and H6 are the protons at position 2 and 6 respectively in the glucosamine unit; HAc is the protons in the N-acetyl group; N–CH₃ are the protons in the N,N,N-trimethyl group.

A Nicolet iZ-10 FTIR instrument (Thermo Fisher Scientific, Waltham, MA, United States) was used to scan starch samples for fourier transform infrared spectra. Starch sample (5 mg) was mixed with 250 mg potassium bromide and pressed into film-coated tablet. The potassium bromide was considered as the background of the tablet. Wavenumbers from 400 to 4,000 cm⁻¹ were measured at 4 cm⁻¹ spectral resolution over 32 scans. The molecular structure of starch was calculated based on the absorbance ratio of 1047/1022 cm⁻¹, 1,022/995 cm⁻¹.

Fourier transform infrared spectra was obtained via scanning starch samples using a Nicolet iZ-10 FTIR instrument (Thermo Fisher Scientific, Waltham, MA, United States). Starch sample (5 mg) was mixed with potassium bromide (250 mg) and pressed into a film-coated tablet. Wavenumbers from 400 to 4,000 cm⁻¹ were measured at 4 cm⁻¹ spectral resolution over 32 scans.