Monosaccharide

Monosaccharides are polyhydroxy aldehydes or ketones which are bonded to hydrogen and oxygen atoms by from 3 to 7 carbon atoms. The simplest monosaccharide is a triose with 3 carbon atoms. With the increase in the number of carbon atoms, there are butanose, pentose and hexose. The important pentose sugars in the human body are ribose and deoxyribose. They make up ribonucleic acid and deoxyribonucleic acid. The three most important biological monosaccharides in biology are glucose, fructose and galactose, and their common chemical formula is C6H12O6. The monosaccharide structure has an aldehyde group or a ketone group, glucose and galactose have an aldehyde group, and fructose has a ketone group. The aldehyde group and the ketone group make the monosaccharide reductive and are used to check whether there is sugar in the urine or blood. Monosaccharides contain a plurality of hydroxyl groups, with typical ester-forming, glycosidation, deoxygenation, dehydration and amination reactions of polyhydric alcohols. Monosaccharides are the basic unit of many sugars. After the sugars in the food are digested into monosaccharides, they are absorbed in the upper part of the small intestine. The absorption rates of various monosaccharides are different, the absorption rate of glucose is 100, the galactose is 110, the fructose is 43, the mannose is 19, the xylulose is 15, and the arabinose is 9. Monosaccharides are essential components of carbohydrates in marine organisms, seawater and marine sediments. The main monosaccharides in marine plankton are (listed in the usual abundance order): galactose, glucose, mannose, ribose, xylose, fucose, rhamnose, arabinose. Most of them exist in the form of polysaccharides or conjugated sugars in living organisms. These monosaccharides are also ubiquitous in seawater and sediments. Fructose lacks a large number of biological sources in the ocean, but can be converted from glucose to isomerization in seawater. The concentration of individual monosaccharides in seawater ranges from 0 to 20 micrograms per liter, typically 10 micrograms of carbon per liter representing the concentration of total free monosaccharides. The content of total free monosaccharides in seawater can be determined by the METH method. The concentration of glucose can be directly determined by enzymatic or bioassay. Simultaneous determination of all individual monosaccharides in seawater samples is generally carried out by chromatography. Since monosaccharides are non-volatile compounds, gas chromatography requires derivatization, and the same monosaccharide appears as a different anomer, giving a complex chromatographic peak. Liquid chromatography is widely used, such as ethanol/water partition chromatography on anion exchange resins, ion exchange chromatography for forming boric acid complexes on borate anion exchange resins, and the like.