Carbohydrates chromatographic methods

There are two basic approaches used to characterize seawater DOM (Benner, 2002). The first of these is to directly analyze bulk compositions (e.g., elemental or isotopic compositions) or individual compounds in the sample without concentration. This approach requires high-sensitivity methods for either broad biochemical types (e.g., total amino acids or carbohydrates) or individual compounds, often by either spectroscopic or chromatographic methods coupled to electrochemical or mass spectro-metric detectors. The latter type of molecular-level analyses are now feasible for measuring individual amino acids (Lindroth and Mopper, 1979), sugars (Skoog et al., 1999), and amino sugars (Kaiser and Benner,... 

Amino Acid/Pimer Analysis. The analysis of dipeptides and the covalent attachment of peptides to carbohydrate was monitored by a high performance liquid chromatographic method (33). 

Borchardet LG, Piper CV (1970) A gas chromatographic method for carbohydrates as alditol acetates Tappi 53 257-260... 

From the known, differential complexing between boronic acids and polyhydroxy compounds, it follows that carbohydrate mixtures may be separated by column-chromatographic methods that exploit the differences. Nucleoside and nucleotide boronates have been separated on columns of anion-exchange resins,90 and sugars and alditols have been shown to be differentially retained on such resins in the sulfonated phenylboronic acid form,64 but perhaps the best uses of column chromatography in this connection have incorporated the resolving powers of insoluble polymers to which boronic acid groups have been covalently bonded. Such insoluble forms of boronates have been synthesized either by substitution of polysaccharide derivatives, or by polymerization of suitable arylboronic acids. 

So far, the tentative chromatographic method has been used to make most of the identifications of the ninhydrin-positive and organic acid components, especially for urine constituents. This simply requires that the unknown peak has the same elution volume as a known reference compound. A significant effort has been made to provide more definite identifications for the components separated by the UV- and carbohydrate analyzers. To date, this has included over 70 UV-absorbing compounds and 18 carbohydrates, some of which are listed in Tables 1-3 (B2, M2). Tentative identification of many more compounds has been made in all four systems, and, hopefully, the efforts in confirmative identification will continue. 

This review outlines current chromatographic methods utilized in the analysis of carbohydrates in biological systems and pharmaceutical products. 

Many plants contain a variety of free acids such as acetic acid, citric acid, fumaric acid, malic acid, succinic acid, oxalic acid, glycohc acid, etc. They are components of citric cycle, whereas the others are intermediates in the pathway from carbohydrates to aromatic com-pounds. Following extraction, organic acids can be separated and detected with a variety of techniques. Thin layer chromatographic methods have been also employed to separate certain organic acids,as presented in Table 3. 

Because of the considerable importance of the analysis of bio-organic compounds in biochemical and biophysical research, many liquid chromatographic methods have been developed and applied for their separation and purity control. There is now growing evidence that PGC columns can contribute considerably to this application area. The flat graphite surface is able to differentiate between closely related compounds such as the structures of several carbohydrates found in nature. 

The GC and HPLC methods were developed for the chromatographic separation of carbohydrates. Gas chromatographic methods are very time consuming, because carbohydrates, owing to their non-volatile character, have to be derivatized prior to the determination [97], On the other hand, the LC method using strong-acid cation exchangers in the calcium form and de-ionized water as the eluent [98] is widespread, but has several drawbacks ... 

The present Chapter includes a description of the general methods and basic principles of gas-liquid chromatography. The development of the method as applied to various classes of carbohydrate derivatives is surveyed, and this treatment is followed by a discussion of mobilities of compounds in relation to their structure. Applications of the method to specific problems are described, and the liquid phases used in gas-liquid chromatography of carbohydrate derivatives are summarized. Finally, an attempt is made to assess the relative merits of gas-liquid chromatography and other chromatographic methods as applied to carbohydrate derivatives. 

Practical applications are again stressed in the Chapter by Lonngren and Svensson (Stockholm) on Mass Spectrometry in Stmctural Analysis of Natural Carbohydrates. They build on the fundamentals of carbohydrate mass spectrometry, as laid down by Kochetkov and Chizhov in Volume 21, and demonstrate the profound analytical value of mass spectrometry for structural analysis of complex polysaccharides. In particular, this tool has dramatically increased the scope of the traditional methylation linkage-analysis procedure, especially when used in conjunction with gas-liquid chromatographic methods of separation. The latter topic is the subject of complementary Chapters by Dutton, one already published in Volume 28 and the other scheduled for publication in Volume 30. 

The hydrolysate (monosaccharide mixture) is analyzed by chromatographic methods. The ion exchange chromatography of the borate complexes of neutral monosaccharides is the most common method, which is used as the basis of fully automatic carbohydrate analysis. 

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