Fourier transform infrared spectroscopic and AC electrical conductivity studies of chitin and its derivatives

Abstract

ABSTRACT:The vibrational modes and the purity index of chitin and its derivatives as biopolymers are studied by Fourier transform infrared spectroscopy in the wavenumber range from 4000 to 400 cm Ϫ1 . The absorption bands of chitin and its derivatives are assigned. New bands appeared at 1419, 1209, 915, and 800 cm Ϫ1 for chitin derivatives due to the change of vibrational modes. The purity indexes are calculated from the ratio of the absorption band of C ϭ O at 1662 cm Ϫ1 and OH at 3443 cm Ϫ1 . Generally, the purity indexes of chitin derivatives are higher than that of chitin, which is due to the decrease of OH. The dielectric properties such as the real part of the dielectric constant (Ј) and loss tangent tan (␦) are measured as a function of temperature at different frequencies ranging from 200 to 2000 kHz. The increase of (Ј) and tan (␦) with increasing temperature is discussed on the basis of increasing polarizability and the decrease with increasing frequency can be attributed to the dielectric dispersion. AC electrical conductivities as a function of the reciprocal of the absolute temperature are also discussed. The mechanism of the charge carrier is discussed as a tunneling model in the temperature range from 300 to 360 K.

Current state of chitin purification and chitosan production from insects

“…The technique, which exploits infrared light to obtain data from excited vibrational states of the functional groups in a sample, enables rapid analysis. According to the functional groups contained in the molecules, the most significant bands of insect-based chitin and chitosan occur at wavenumbers of 1310-1320 cm −1 (CN stretching, amide III), 1550-1560 cm −1 (NH bending, amide II), 1590-1600 cm −1 (NH 2 bending), 1650-1655 cm −1 (CO stretching, amide I), 3100-3110 cm −1 (NH symmetric stretching), 3255-3270 cm −1 (NH asymmetric stretching) and 3430-3450 cm −1 (OH stretching) 170,171 (Fig. 3).…”

A Protocol for Radiocarbon Dating Tropical Subfossil Cave Guano

“…Both samples of fossil IC (GAN 1 and GAN 2) subjected to FTIR analysis contain a range of signals characteristic of the chitin macromolecule. Secondary amides are represented at 3270 cm -1 for symmetric NH stretching, and between 2880 and 2960 cm -1 for CH stretching vibrations (Seoudi et al 2005). Although visible, these signals are much weaker in the spectra for the fossil samples when compared to fresh guano.…”

“…Absorbance values were determined over the range 4000-400 cm 1 . Spectral bands were identified by comparison with published assignments for natural chitin and N-acetyl-D-glucosamine, the monomeric unit of the chitin polymer (Focher et al 1992;Seoudi et al 2005).…”

Stable Isotopes of Subfossil Bat Guano as a Long-Term Environmental Archive: Insights from a Grand Canyon Cave Deposit

“…4). Bands at 3448, 3269, and 2934 cm 21 represent OH stretching and symmetric NH stretching in secondary amides, respectively, while CH symmetric and asymmetric stretching vibrations were observed between 2828 and 2962 cm 21 (Seoudi et al, 2005). Detailed information is contained in the fingerprint region at 900-1700 cm…”

“…Here, bands at 1653 and 1557 cm 21 relate to CO stretching in amide I and N-H deformation of amine II, and at 1381 cm 21 to CH bending vibration in chitin ( Van de Velde and Kiekens, 2004;Seoudi et al, 2005). Finally, bands at 1030 to 1156 cm 21 are diagnostic for ring and bridge C-O-C vibrations in the saccharide monomer (Duarte et al, 2002).…”