Acid Hydrolysis Of Chitosan Research Articles

Determination of chitosan content with ratio coefficient method and HPLC

The determination of chitosan is a significant topic that has been growing in importance for a variety of fields. To quantify chitosan, various analytical methods can be used. When high performance liquid chromatographic (HPLC) is used for quantitative analysis of chitosan, the chitosan is mainly hydrolyzed into glucosamine salts, which are determined by HPLC. Average deacetylation degree (DD) has an effect on acid hydrolysis of chitosan. In this paper, chitosan with different average DDs was hydrolyzed to observe its effect on the determination of chitosan content, and that the study of combining acid hydrolysis rates of chitosan (α) with different average DDs and chitin (β) standard to form ratio coefficients (γ) to quantify chitosan was designed. Then, the table about γ values within certain average DD ranges of chitosan was obtained. By using γ and α, the actual content of chitosan could be obtained simply and accurately.

Effect of re-acetylation on the acid hydrolysis of chitosan under an induced electric field

This study explored the impact of re-acetylation on induced electric field (IEF)-assisted hydrolysis of chitosan. Chitosan with different degree of deacetylation (DD) exhibited different charge content but similar electrical conductivity and output voltage of the electrolyte system, thus theoretically resulting in equivalent electro-processing efficiency. However, molecular and rheological measurements suggested that the hydrolysis rate decreased with an increase of DD. Re-acetylation had no significant effect on the molecular weight and viscosity of chitosan but damaged its granular and crystal structure, making chitosan chains more susceptible to the acid. The IEF-assisted hydrolysis of dissolved chitosan confirmed that the structural compactness of chitosan played a more important role on the hydrolysis than the charge content. This study extended current knowledge regarding the effect of charge content and structural compactness on IEF-assisted hydrolysis process, which contributed to the applications of IEF in biopolymer modification.

Extraction and characterization of chitin, chitosan and chitooligosaccharides from crab shell waste

An experiment was carried out to utilize the crab shell waste for the production of chitin by chemical extraction method. The obtained chitin was processed to make the more useful compound chitosan by deacetylation of chitin using strong NaOH solution at high temperature. Yield of chitin and chitosan from crab shell waste was found to be 12.2 % and 10.54 %, respectively. Chitosan was further used to produce chito-oligosaccharides (COS) by acid hydrolysis using 0.5 N H2SO4, 1N H2SO4 and 7N HCl at hourly intervals upto 6 hours and the average yield was 0.55, 0.84 and 1.93 mg/ml, respectively. Chitin and chitosan were characterized by Fourier Transform Infrared spectroscopy (FT-IR) technique which depicts different band representing various bonds present in the molecule and which were in agreement with the bands of standard chitin and chitosan. Further, COS were formed after acid hydrolysis of chitosan, which was characterized by Thin Layer Chromatography (TLC) using glucosamine as a standard.

Structure and Sorption Characteristics of Nanocrystallites of Chitosan

The structural features and thermal and sorption characteristics of nanocrystallites of chitosan, produced by hydrolysis and alcoholysis of high-molecular chitosan, were examined. The nature of the changes in the supramolecular structure and characteristics of the nanoparticles (degree of crystallinity, geometric dimensions of the crystallites, specific surface area) that are most significant in the nanocrystallites produced during precipitation of the products from homogeneous sulfuric acid hydrolysis of chitosan with NaOH solution is presented on the basis of data from thermogravimetric analysis, atomic-force microscopy, NMR relaxometry, and calculation of the sorption isotherms.

Separation of chito-oligomers with several degrees of polymerization and study of their antioxidant activity

Chitooligomers (COS) with degree of polymerization (DP) ranging from 2 to 12 was prepared by acid hydrolysis of chitosan and five fractions were separated from the prepared COS by CM Sephadex C-25 column. The fractions were desalted by activated charcoal extraction. The components of each fraction were analyzed by TLC, HPLC and MALDI-TOFMS. Five fractions mainly contained trimer (95.7%), tetramer and pentamer (90.9%), pentamer (85.6%), hexamer (89.5%) and heptamer to decamer (94.7%), respectively. The antioxidant activities of each fraction and COS mixture were investigated, including hydroxyl and superoxide radical scavenging activity and reducing power. The activities of the six COSs were in a dose-dependence manner and related to their DP. The COS with low DP showed better effect of scavenging hydroxyl radical and reducing power than that with high DP. In contrast, the superoxide radical scavenging activity of all the tested COSs increased with DP increasing. (C) 2012 Elsevier Ltd. All rights reserved.