Preparation of low-molecular weight alginic acid by acid hydrolysis

2000 ◽  
Vol 42 (4) ◽  
pp. 421-425 ◽  
Author(s):  
A. Ikeda ◽  
A. Takemura ◽  
H. Ono
Keyword(s):  
Molecular Weight ◽  
Acid Hydrolysis ◽  
Alginic Acid ◽  
Low Molecular Weight

Photosynthesis and metabolism of marine algae. VIII. Incorporation of 14C into the polysaccharides metabolized by Fucus vesiculosus during pulse labeling experiments

1972 ◽  
Vol 50 (1) ◽  
pp. 191-197 ◽  
Author(s):  
R. G. S. Bidwell ◽  
Elizabeth Percival ◽  
Berit Smestad
Keyword(s):  
Molecular Weight ◽  
Sequential Extraction ◽  
Marine Algae ◽  
Alginic Acid ◽  
Fucus Vesiculosus ◽  
Fresh Medium ◽  
Low Molecular Weight ◽  
Acid Extract ◽  
Highly Active ◽  
Residual Material

Samples of Fucus vesiculosus fronds were allowed to assimilate 14CO2 for 10 min and 3 h. In a second experiment fronds were allowed to grow for 10 min in 14CO2 and were then transferred to fresh medium containing 12CO2. Samples were taken immediately, after 30 min, and after 2 h. Sequential extraction and fractionation of the polysaccharides from each of the five samples gave 14C-labeled laminaran, xylogalactofucoglucuronan (A), xyloglucuronogalactofucan (B) (these polysaccharides are named in the order of the increasing proportions of their constituent sugars), fucoidan (C), alginic acid, and residual polysaccharide material containing mainly glucose with some galactose. The activities of each of the polysaccharides, the residual material, and their constituent sugars were measured. Highly active low molecular weight carbohydrates, present in the acid extract, are the suggested precursors of the polysaccharides. The fucose-containing polysaccharides represent the extremes of a family of polymers; it is postulated from these studies that (A) is transformed into fucoidan via polysaccharide (B) in this alga.

scholarly journals PREPARATION AND CHARACTERIZATION OF LOW MOLECULAR WEIGHT CHITOSAN WITH DIFFERENT DEGREES OF DEACETYLATION BY THE ACID HYDROLYSIS METHOD

2021 ◽  
pp. 153-164
Author(s):  
NAWZAT D. AL-JBOUR ◽  
M. D. H. BEG ◽  
JOLIUS GIMBUN ◽  
A. K. M. MOSHIUL ALAM
Keyword(s):  
Molecular Weight ◽  
Acid Hydrolysis ◽  
Water Solubility ◽  
Skeletal Structure ◽  
Low Molecular Weight ◽  
Molecular Weights ◽  
Hydrolysis Method ◽  
Significant Difference ◽  
Low Molecular Weight Chitosan ◽  
Pharmaceutical Industries

Objective: The objective of this research is to prepare Low Molecular Weight Chitosan (LMWC) by the acid hydrolysis method, using dilute hydrochloric acid (2M). LMWC has superior properties compared to the High Molecular Weight Chitosan (HMWC), especially in terms of water solubility, antibacterial and antifungal properties. These could open new potential applications for LMWC in sectors such as the cosmetics, food, and pharmaceutical industries. Methods: In this work, the acid hydrolysis method was used to produce LMWC with different molecular weights starting from 500 kDa and 93% degree of deacetylations (DDA). The molecular weights of the produced grades were determined by applying Mark-Houwink equation while the %DDA was determined and verified by the use of the 1st derivative UV method and 1HNMR method, respectively. The depolymerization reactions were carried out with different time intervals to produce totally deacetylated LMWC of 30 kDa, 15 kDa, and 7.5 kDa. The LMWC was characterized by FTIR, XRD, and DSC to evaluate the functionality, microstructure and thermal properties. Results: The FTIR spectra revealed that there is no significant difference in the main skeletal structure of the LMWC and HMWC. On the other hand, the XRD and DSC results showed that the LMWC of different molecular weights and degrees of deacetylation are of semi-crystalline structure, similar to the HMWC. Conclusion: The obtained results showed that the used acid hydrolysis procedure can produce LMWC grades of desired specifications, yields, and quality which are suitable for use in different applications.

scholarly journals Production of Low Molecular Weight Chitosan and Chitooligosaccharides (COS): A Review

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2466
Author(s):  
Cleidiane Gonçalves ◽  
Nelson Ferreira ◽  
Lúcia Lourenço
Keyword(s):  
Molecular Weight ◽  
Acid Hydrolysis ◽  
High Specificity ◽  
Added Value ◽  
Limiting Factor ◽  
Low Molecular Weight ◽  
Hydrolysis Time ◽  
Power Intensity ◽  
Low Molecular Weight Chitosan ◽  
Long Time

Chitosan is a biopolymer with high added value, and its properties are related to its molecular weight. Thus, high molecular weight values provide low solubility of chitosan, presenting limitations in its use. Based on this, several studies have developed different hydrolysis methods to reduce the molecular weight of chitosan. Acid hydrolysis is still the most used method to obtain low molecular weight chitosan and chitooligosaccharides. However, the use of acids can generate environmental impacts. When different methods are combined, gamma radiation and microwave power intensity are the variables that most influence acid hydrolysis. Otherwise, in oxidative hydrolysis with hydrogen peroxide, a long time is the limiting factor. Thus, it was observed that the most efficient method is the association between the different hydrolysis methods mentioned. However, this alternative can increase the cost of the process. Enzymatic hydrolysis is the most studied method due to its environmental advantages and high specificity. However, hydrolysis time and process cost are factors that still limit industrial application. In addition, the enzymatic method has a limited association with other hydrolysis methods due to the sensitivity of the enzymes. Therefore, this article seeks to extensively review the variables that influence the main methods of hydrolysis: acid concentration, radiation intensity, potency, time, temperature, pH, and enzyme/substrate ratio, observing their influence on molecular weight, yield, and characteristic of the product.

scholarly journals Low-molecular-weight solutes released during mild acid hydrolysis of the lipopolysaccharide of Pseudomonas aeruginosa. Identification of ethanolamine triphosphate

1972 ◽  
Vol 130 (1) ◽  
pp. 289-295 ◽  
Author(s):  
David T. Drewry ◽  
George W. Gray ◽  
Stephen G. Wilkinson
Keyword(s):  
Molecular Weight ◽  
Pseudomonas Aeruginosa ◽  
Acid Hydrolysis ◽  
Decomposition Product ◽  
Lipid A ◽  
Careful Examination ◽  
Low Molecular Weight ◽  
Mild Acid Hydrolysis ◽  
Hydrolysis Of ◽  
Mild Acid

A careful examination of the low-molecular-weight solutes released during mild acid hydrolysis of the lipopolysaccharide of Pseudomonas aeruginosa (N.C.T.C. 1999) revealed the presence of ethanolamine triphosphate. During storage, the compound decomposed to give ethanolamine pyrophosphate, identified in a previous study (Drewry et al., 1971); PPi may be a further decomposition product. Evidence for the attachment of ethanolamine triphosphate to a polysaccharide fraction was obtained, but the possibility that some was attached to the lipid A moiety was not excluded. Basic compounds released during the hydrolysis of lipopolysaccharide included amino acids, polyamines and oligopeptides.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

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