Polysaccharides are polymers (generally more than 10) in which aldoses and/or ketoses present in nature are linked by glycosidic bonds. Polysaccharide is an essential component of all living organisms, and it is closely related to the various physiological functions that sustain life. There are many methods for determining the content of crude polysaccharides. One is to use the reducibility of polysaccharides. The methods for determining reducing polysaccharides are 3, 5-dinitrosalicylate (DNS) colorimetry and Somogyi-Nelson method. . Another type of measurement method, which is now commonly used, is the use of polysaccharides to dehydrate under strong acidic conditions to form furfural or its derivatives, and then condense with phenols or amines to form a substance with a special color. The measurement is carried out by a method such as a lichenol-sulfuric acid method, a phenol-sulfuric acid method, and an anthrone-sulfuric acid method.
The phenol-sulfuric acid method is used in a large amount. The phenol-sulfuric acid reagent can react with free oligosaccharides, hexoses and uronic acids in polysaccharides, and the maximum absorption value of hexose at 490 nm, absorption value. It is linear with sugar content. In this method, the standard curve is prepared by standard sugar, and then the absorbance is measured by the color reaction of the polysaccharide, and then the concentration of the polysaccharide is calculated according to the position on the curve to estimate the content. This method is simple, fast, sensitive, and reproducible. Only one standard curve is required for each sugar. The anthrone-sulfuric acid method is another commonly used method. The principle is that the sugar is dehydrated with concentrated sulfuric acid to form a alditol or a derivative thereof, which can be condensed with an anthrone reagent. After the reaction, the solution is blue-green at 620 nm. There is maximum absorption, and the depth of color development is linear with the content of polysaccharide.
Product Name: Dextran Dextran
CAS NO: 9004-54-0
Molecular formula: C6nH10nO5n
Brand
Product name model
Item number
Packing specification
Market price
discount price
Pefermiker
Dextran 5, Dextran, molecular weight 5000
C16-D104010-25g
25g
348.00
278.00
Pefermiker
Dextran 5, Dextran, molecular weight 5000
C16-D104010-100g
100g
1596.00
1276.00
Pefermiker
Dextran 5, Dextran, molecular weight 5000
C16-D104010-500g
500g
3987.00
3189.00
Pefermiker
Dextran 40, Dextran, molecular weight 40,000
C16-D104008-25g
25g
142.40
114.00
Pefermiker
Dextran 40, Dextran, molecular weight 40,000
C16-D104008-100g
100g
309.00
247.00
Pefermiker
Dextran 40, Dextran, molecular weight 40,000
C16-D104008-500g
500g
1268.00
1014.00
At present, there is widespread controversy in the selection of standards for the production of standard curves. Glucose has always been the first choice for researchers because of its low price and convenient source. But when we delved into the principle of colorimetry and found that it could not distinguish between monosaccharides and oligosaccharides, its measurement results largely depended on the choice of standards. In addition, the colorimetric method usually uses concentrated sulfuric acid to hydrolyze the crude polysaccharide for a short time. For the crude polysaccharide with a small molecular weight, the high concentration of sulfuric acid can be hydrolyzed into oligosaccharides and monosaccharides in a relatively short time, but when the molecular weight of the crude polysaccharide is higher When large, hydrolysis is difficult to control. For example, complete hydrolysis of crude polysaccharides (molecular weight 500,000~1,000,000) requires 4M HCl or 2M H2SO4 for 3-6 hours at 100 °C. Therefore, if glucose is used as a standard curve, it is bound to bring a large error to the measurement of the macromolecular portion of the crude polysaccharide sample. Therefore, the research data of scholars at home and abroad show that: 1) For the colorimetric method, when the standard and the sample are similar in structure, the results are much more accurate [1]; 2) using glucose as a standard and When dextran is used as a standard to measure the content of crude polysaccharides, the results measured by the former are somewhat higher [2, 3]. In this way, it is not appropriate to use glucose as a standard for determining the polysaccharide content.
Oat β-glucan is a β-(1→3)-(1→4)-bonded linear glucan, which is similar to common plant and fungal polysaccharides in other physical properties such as structure and viscosity. As a standard for the determination of polysaccharide content in plant and fungi sources. However, due to the difficulty in purifying the polysaccharide, many glucans on the market have low purity and are not suitable as standard products.
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