Sugars mass spectra

Peaks at m/e 113 and 85 have been found in the mass spectra (12) of other O-isopropylidene ketals of sugars, as well as in Figure 7. Since these shift to m/e 119 and to m/e 88 and 91 in the mass spectrum of 10a as they did for the d6-analogs in Reference 12, the structures, 17, 18, and 19 from Reference 12 are shown as possible explanations. The peak at m/e 85 (91) could alternatively be from m/e 113 (119) by loss of carbon monoxide (28 mass units) from the six-membered-ring of structure 17b. 

Figure 13.4 presents the mass spectrum and distribution of the molecular ion of salbutamol (mass 240 u), the asthma drug, which is commercially produced as a coating on micron-sized sugar beads. For analysis a Bi3++ cluster gun was used. Before measurements the sample was sprayed onto a silicon substrate in order to disperse the beads [7],... 

Separation of the partially methylated sugars by g.l.c. gives evidence on the methyl-substitution pattern complementary to that obtained from the mass spectrum. The electron-impact, mass spectra do not differentiate between the sugar isomers (such as the galactose,... 

The u-deoxy sugars studied (6-deoxy and 5-deoxy) have intense peaks for the dithioacetal fragment, and also break down to Fragments A, B, and C. < -Deoxyhexose dithioacetals cannot be differentiated from 5-deoxy-hexose dithioacetals. The deoxy function is, apparently, too far removed from the bonds most susceptible to cleavage to have a significant effect. Mass spectrometry can also be useful in the characterization of terminal branched-chain deoxy sugars. The spectrum of 6-deoxy-5-C-methyl-D-xylo-hexose diethyl dithioacetal 1 contains prominent peaks due to Fragments A, B, and C. Apparently, substitution beyond C-4 does not affect... 

Extended tables of gas-phase proton affinity exist. This is not true for the affinity towards metal ions. To attach a proton a basic site is needed. Binding a sodium ion requires the availability of several electron pairs in its surrounding. Sugars for example are not basic, but a sodium ion may find many electron pairs. This is why the protonated molecule is difficult to observe in the mass spectrum if the solution is not carefully desalted. Otherwise,... 

Thirty years ago, the linkage of HPLC to MS seemed a physical impossibility because of two main hindrances. The first problem was how to get rid of the eluent without losing the compounds to be analyzed. Secondly, we must realize that, to obtain the mass spectrum of a compound, it is necessary to have it in the vapor state and in an ionized form. We must also remember that many phenols, especially those linked to sugars, are not volatile and are thermolabile. 

At one time the idea of recording a mass spectrum of a nucleic acid would have been considered utopic and futuristic. Nucleic acids are practically nonvolatile and usually possess a molecular weight of several million atomic mass units (amu) (fi) often expressed in daltons up to 10 daltons where 1 dalton = 1.67 X 10 g. They possess their own mass spectra. In general they are esters of phosphoric acid and polyols, such as the sugars ribose and 2 -deoxyribose, which are themselves substituted with heteroaromatic purine or pyrimidine bases. Consequently, fragment ions characteristic of all these structural elements can be found in the mass spectra of nucleic acids. 

Holacurtinol (40) is a minor alkaloid. The mass-spectrum showed fragments attributable to successive losses of two molecules of HjO suggesting the presence of two hydroxyl groups. The NMR spectral data showed the presence of the same sugar unit (4-deoxy-4-amino-P-D-cymaropyranose) as in 37 and 39, while the pregnane aglycone portion was similar to that of... 

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