Sugar Mixtures, Analysis

Ammonia, like carbon dioxide, is not over-common in periodate oxidation mixtures but it is quite important when it does appear, as in the oxidation of aminodeoxy sugars. The analysis for ammonia has been successfully performed using a Van Slyke-Neill apparatus,102 106 and by distillation and titration.78... 

Only model studies have so far been reported, and the method has not yet been applied to the analysis of sugar mixtures, with the exceptions noted.48,49 The recovery of glucose-14C trifluoroacetate from a column of Carbowax 20 M or SF-96 has been shown to be 5 to 14% and 3 to 5%, respectively.208 Table III (p. 112) records further details of the separation of sugars and their derivatives as trifluoroacetates. 

Until the advent of paper chromatography, quantitative analysis of sugar mixtures, except of those of simple composition, was both difficult... 

Chromatographic Analysis of Wood Sugars. This analysis requires acid hydrolysis of the polysaccharide to yield a solution mixture of the five wood sugar monomers, i.e., glucose, xylose, galactose, arabinose, and mannose. The solution is neutralized, filtered. 

Sugar Analyses. Hydrolyses of polysaccharide fractions and cell trail preparations were performed (a) directly with trlfluoroacetic acid ( ) and (b) after digestion with 72% sulfuric acid and dilution, with M-sulfuric acid (O. Allose was added as an Internal standard and the sugar mixtures were converted Into alditol acetates (12) for analysis by glc on column (a). Uronlc acid determlnaclons were carried out spectrophotometrlcally with the 3-hydro3qrdlphenyl reagent ( ). In the case of Insoluble materials determinations were performed after digestion with 72% sulfuric acid and appropriate dilution. 

Thin-layer chromatography affords a simple, rapid and sensitive method for the qualitative and quantitative analysis of low molecular weight sugars and their derivatives. In the few years since Stahl and ELaltenbach [1] extended TLC to the separation of sugar mixtures, the method has been adopted for a wide spectrum of analytical problems. This chapter considers two classes of compounds the hydrophilic carbohydrates and their derivatives which are hydrophobic in nature. 

On the other hand, the kinetic reduction waves of aldopentose hydrazones, obtained by adding the pentose to 0-053 M dibasic sodium phosphate containing 0-1 M hydrazine sulphate (final pH 2-3), can be used for analytical purposes.The governing chemical reaction, and hence the limiting current too, are pH dependent, and it is therefore necessary to control the pH carefully. Owing to differences in equilibrium and/or, rate constants, the limiting currents at pH 2-3 vary substantially for different pentoses. This can be utilized for the analysis of certain sugar mixtures. 

Analysis of only the simplest sugar mixtures is generally required for pharmaceutical preparations and the subject will be discussed briefly and yet in sufficient detail for undertaking the estimation of simple sugars or mixtures of sucrose, invert sugar and glucose or lactose. 

Figure 5.31 LC-electrospray-MS-MS spectrum of the column eluate at around 22 min in the analysis of the peptide mixture from the tryptic digest of glycoprotein TIME-EA4 from silkworm diapause eggs. Reprinted from Bioorg. Med. Chem., 10, Kurahashi, T., Miyazaki, A., Murakami, Y., Suwan, S., Franz, T., Isobe, M., Tani, M. and Kai, H., Determination of a sugar chain and its linkage site on a glycoprotein TIME-EA4 from silkworm diapause eggs by means of LC-ESI-Q-TOF-MS and MS/MS , 1703-1710, Copyright (2002), with permission from Elsevier Science.

As the name implies, the odor of urine in maple syrup urine disease (brancbed-chain ketonuria) suggests maple symp or burnt sugar. The biochemical defect involves the a-keto acid decarboxylase complex (reaction 2, Figure 30-19). Plasma and urinary levels of leucine, isoleucine, valine, a-keto acids, and a-hydroxy acids (reduced a-keto acids) are elevated. The mechanism of toxicity is unknown. Early diagnosis, especially prior to 1 week of age, employs enzymatic analysis. Prompt replacement of dietary protein by an amino acid mixture that lacks leucine, isoleucine, and valine averts brain damage and early mortality. 

All these methods give similar results but their sensitivities and resolutions are different. For example, UV-Vis spectrophotometry gives good results if a single colorant or mixture of colorants (with different absorption spectra) were previously separated by SPE, ion pair formation, and a good previous extraction. Due to their added-value capability, HPLC and CE became the ideal techniques for the analysis of multicomponent mixtures of natural and synthetic colorants found in drinks. To make correct evaluations in complex dye mixtures, a chemometric multicomponent analysis (PLS, nonlinear regression) is necessary to discriminate colorant contributions from other food constituents (sugars, phenolics, etc.). 

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