Fourier transform infrared (FT-IR) spectroscopic investigations of four agarophytes from northern Arabian sea

Abstract

The fresh specimens of Champia compressa Harvey, Gelidium usmanghanii Afaq-Husain and M. Shameel, Gracilaria foliifera (Forsskål) Børgesen and Hypnea musciformis (Wulfen) J. V. Lamouroux, were collected from the coastal areas of Karachi (Pakistan) and their yield of agar was observed. With preextraction technique the percentage of algal yield was found to range from 13 to 28%. High quality gel strength was determined by modulus of elasticity i.e. (550 – 612g/cm2) and 1090 kPa and extraction time was 2 hrs. The structure of agar and agar contents were investigated by FT-IR spectroscopy for the first time from Pakistan. The results revealed some interesting characters (non sulphated β-D galacto pyranose residues, 3,6 anhydro galactose vibration), which were not reported earlier.

Gel Biopolymer Electrolytes Based on Saline Water and Seaweed to Support the Large‐Scale Production of Sustainable Supercapacitors

“…The FTIR spectrum (Figure 1a) showed the vibrational modes of the chemical bonds in the biopolymer. Table 1 summarizes the wavenumbers associated with the vibrational modes in the unmodified agar and modified agar (AG‐1M), corroborating previous works [20–22] . The main bands are observed in the region between 800 and 1300 cm −1 .…”

“…Table 1 summarizes the wavenumbers associated with the vibrational modes in the unmodified agar and modified agar (AG-1M), corroborating previous works. [20][21][22] The main bands are observed in the region between 800 and 1300 cm À 1 . The bands at 882 and 890 cm-1 are attributed to CÀ H bending at the anomeric carbon in β galactopyranosyl residues.…”

Дослідження Інфрачервоних Спектрів Гелевих Систем На Основі Агару Для Виробництва Желейних Батончиків

“…1, 2, sample 5) stretching vibrations of the associated hydroxyl groups are represented by an intense wide absorption band in the region 25001800 cm -1 with a maximum of 2139 cm -1 caused by the formation of a significant number of intermolecular hydrogen bonds in chains with different molar mass. Compared with a spectrum of liquid water (et 2150 cm -1 ) [23,24] the maximum of the gel absorption band shifts towards the smaller wave numbers, the intensity of the band increases, as well as the intensity of the band of its bending component (et 1645 cm -1 ). At the same time, the band of symmetric stretching (3450 cm -1 ) significantly expands in the spectrum due to the formation of new hydrogen bonds between carbon chains with different molar masses.…”

“…Frequency positions (cm -1 ) of the main bands of the IR spectra of the absorption of functional groups of agar and glycerol before and after the interaction Wave number, cm In the IR spectrum of agar (3 mg pre-dried to constant weight of the sample / 300 mg KBr) there are the following bands of absorbtion: intense bands corresponding to stretching of OH, NH bonds and fluctuations of adsorption band of water (in the range of 36003200 cm -1 with a maximum of 3400 cm -1 ); band for antisymmetric stretching of CH bonds in methoxyl groups OCH3 (at 2924 cm -1 ); C=O symmetric stretching and NH bending in conjugated peptide bond in pectin substances (at 1644 cm -1 ); S=O symmetric stretching in sulfate ester; methyl group vibration (at 1374 cm -1 ); band of symmetric stretching of SO, CO bonds common to all agar sulfate groups (at 1248 cm -1 ); average intensity bands characteristic to CH2 bending of pyranose ring of 3,6anhydrogalactose (at 1072, 930 cm -1 ); CC, CO, COS stretching, СОН bending represented by weak band characteristic to galactose-4-sulfate (at 857 cm -1 ) and weak band characteristic to 3,6anhydrogalactose-2-sulfate (at 812 cm -1 ). Literature data describes the analogous values for characteristic bands of agar sample [22,23,24].…”