Sugars spectroscopy

Sucrose quantitation has also been performed by colorimetric methods. However, in recent years, automated enzymatic analyzers and instmmental methods (eg, ion chromatography and hplc) have become increasingly popular, as they provide greater sensitivity and accuracy. Near infrared (nir) spectroscopy is currendy under evaluation as a tool for sucrose quantitation in sugar mills and food processing operations. 

Other methods of identification include the customary preparation of derivatives, comparisons with authentic substances whenever possible, and periodate oxidation. Lately, the application of nuclear magnetic resonance spectroscopy has provided an elegant approach to the elucidation of structures and stereochemistry of various deoxy sugars (18). Microcell techniques can provide a spectrum on 5-6 mg. of sample. The practicing chemist is frequently confronted with the problem of having on hand a few milligrams of a product whose structure is unknown. It is especially in such instances that a full appreciation of the functions of mass spectrometry can be developed. 

Studies of Deoxy Sugars by Proton Magnetic Resonance Spectroscopy... 

The first three carba-sugars were synthesized by McCasIand and coworkers. Two other carba-sugars were prepared from myoinositol, and the remaining eleven carba-sugars have been synthesized from the Diels-Alder adduct of furan and acrylic acid. Conformational assignments of the carba-sugars were established with the aid of H-n.m.r. spectroscopy. 

NMR spectroscopy To identify specific sugars, their sequence, linkages, and the anomeric nature of glycosidic linkages. 

Cello- and malto-oligosaccharides up to nonasaccharides in the presence of various metal salts have been analyzed by f.a.b.-m.s. The structures of two methyl alduronates obtained by flash hydrolysis of wood chips was deduced by using f.a.b.-m.s., n.m.r. spectroscopy, and sugar analysis. ... 

Amide derivatives have proved especially useful sugars for study by c.d. spectroscopy. The amide substituent is the same as the chromophore found in proteins, so that its optical properties have been extensively studied both experimentally and theoretically. 2-Acetamido sugars are found in many glycoproteins. The structure of 2-acetamido-2-deoxy-a-D-glucopyranose is given as an example in formula 7. 

The significance of n.m.r. spectroscopy for structural elucidation of carbohydrates can scarcely be underestimated, and the field has become vast with ramifications of specialized techniques. Although chemical shifts and spin couplings of individual nuclei constitute the primary data for most n.m.r.-spectral analyses, other n.m.r. parameters may provide important additional data. P. Dais and A. S. Perlin (Montreal) here discuss the measurement of proton spin-lattice relaxation rates. The authors present the basic theory concerning spin-lattice relaxation, explain how reliable data may be determined, and demonstrate how these rates can be correlated with stereospecific dependencies, especially regarding the estimation of interproton distances and the implications of these values in the interpretation of sugar conformations. 

Daniel-Kelly, J. F., Downey, G., and Fouratier, V. (2004). Initial study of honey adulteration by sugar solutions using midinfrared (MIR) spectroscopy and chemometrics. /. Agric. Food Chem. 52, 33-39. 

Irudayaraj, J., Xu, F., and Tewari, J. (2003). Rapid determination of invert cane sugar adulteration in honey using FTIR spectroscopy and multivariate analysis. /. Food Sci. 68, 2040-2045. 

Sivakesava, S. and Irudayaraj, J. (2001b). Prediction of inverted cane sugar adulteration of honey by Fourier transform infrared spectroscopy. /. Food Sci. 66, 972-978. 

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