Alditols acetals, mass spectrometry

Steinberg, R, and Fox, A. (1999), Automated derivatization instrument Preparation of alditol acetates for analysis of bacterial carbohydrates using gas chromatography-mass spectrometry, Anal. Chem.,11,1914-1917. 

The proposed structure is in full agreement with the results obtained by mass spectrometry, immunodiffusion and analysis of partially methylated alditol acetates (4). 

Figure 1. Methylation linkage analysis of PSL-I by GC/MS total ion chromatogram of partially methylated alditol and myoinositol acetates (PMAA) from PSL-I carboxyl-reduced trisaccharide by gas chromatography /mass spectrometry in...

Whiton, R. S., Lau, P., Morgan, S. L., Gilbart, J., and Fox, A. (1985). Modifications in the alditol acetate method for analysis of muramic acid and other neutral and amino sugars by capillary gas chromatography-mass spectrometry with selected ion monitoring. /. Chromatogr. A 347, 109—120. 

Carpita NC, Shea EM (1989) Linkage structure of carbohydrates by gas chromotography-mass spectrometry (GC-MS) of partially methylated alditol acetates. In Biermann CJ, McGinnis GD (eds) Analysis of carbohydrates by GLC and MS. CRC Press, Boca Raton, FL, p 157... 

Methylation is the most widely used method to determine the position of the glycosyl linkages.Permethylation of glycolipids can be done according to the methods of Hakomori (32) and Ciucanu and Kerek (33). The permethylated derivatives are hydrolyzed and the products converted into partially methylated alditol acetates and identified by gas chromatography-mass spectrometry ( CG-MS) (34). 

Funakoshi, I., Yamashina, I. (1980). Quantitative determination of partially methylated alditol acetate of amino sugar by gas chromatography-mass spectrometry. Analytical Biochemistry, 107, 265 270. 

Analysis of a hydrolyzate of the lipopolysaccharide from Pasteurella pseudotuberculosis Group IIA, by g.l.c. of the derived alditol acetates, revealed an unknown component. Mass spectrometry of the alditol acetate obtained after reduction with sodium borodeuteride showed a fragmentation mode compatible with the alditol acetate from a 6-deoxy-heptose. The sugar was subsequently identified as 6-deoxy-D-manno-heptose. ... 

Methyl glycosides are of their greatest use when only a few methylated sugars are anticipated, as with polysaccharides of simple structure and, in particular, with oligosaccharides. They are useful where identification must be based on peak profile and retention times, but, when characterization is to be achieved by mass spectrometry, other derivatives, such as alditol acetates, are preferable (see Section XXI,2 p. 30). Glycosides have the advantage over alditols that they may be hydrolyzed to the free sugar for further characterization. 

With the advent of column packings capable of separating alditol acetates (see Part I, Section VII,2 p. 59), these derivatives were first utilized by Lindberg and coworkers, who showed that the same liquid phase (ECNSS-M) is suitable for the separation of these compounds having all degrees of methylation. The simplicity of the chromatogram, coupled with the fact that the pattern of methylation in alditol acetates may readily be determined by mass spectrometry (see Section XXV ... 

Much of the earlier work on the mass spectrometry of carbohydrates was discussed in this Series by Kochetkov and Chizhov, and the same authors have presented certain practical aspects of the technique. Hanessian described the application of mass spectrometry to natural products containing sugars, and other reviews have been written by Rosenthal and Heyns and coworkers. Lindberg and coworkers discussed the combined use of gas-liquid chromatography and mass spectrometry (g.l.c.-m.s.) with reference to alditol acetates and, elsewhere in this Series (see Vol. 29, Chapter 3), Ldnngren and Svensson amplified this topic. The purpose of the present Section is to collate those literature reports relevant to the determination of polysaccharide structures, but not to discuss such matters as the mechanism by which the fragments are formed, information on which can be found in the reviews and articles mentioned. 

The use of alditol acetates for the separation of mixtures of partially methylated sugars not only simplifies the g.l.c. but also the mass spectra, because such compounds contain carbon to carbon bonds of only three types those between (a) carbon atoms that each carries a methoxyl group, or (b) each bears an acetoxyl group, or (c) adjacent carbon atoms having one substituent of each type. Mass spectrometry of partially methylated alditol acetates thus gives rise to relatively few primary fragments that are characteristic of the pattern of substitution. This technique was introduced to carbohydrate chemistry by Lindberg and his associates, and has been employed extensively by them in subsequent structural studies, some of which are discussed next others are listed in Table XXXI (see p. 103). 

The use of mass spectrometry in the structural analysis of carbohydrates, first reported in 1958 (114), was developed in detail by Kochetkov and Chizhov (115). They showed that, under electron impact, the acetylated and methyl ether derivatives of monosaccharides provided a wealth of structural information through analysis of typical fragmentation pathways of the initial molecular ion. This has proved of enormous utility in the structural elucidation of polysaccharides and complex oligosaccharides sequential permethylation, hydrolysis, reduction to the alditol, and acetylation, affords mixtures of peracetylated, partially methylated alditol acetates that can be separated and analyzed by use of a gas chromatograph coupled directly to a mass spectrometer (25). The mass spectra of stereoisomers are normally identical, while the gas chromatographic retention times readily permit differentiation of stereoisomers. 

A remarkably selective conversion of formaldehyde into glucose was reported by Weiss and co-workers.The reaction, carried out at 98°, was initiated by adding aqueous sodium hydroxide to a calcium chloride-formaldehyde solution. Under these conditions the induction period was IS seconds, and at 18% formaldehyde conversion level hexoses were formed with 84.3% selectivity. Analysis by glc of the products [in the form of trimethyl silyl (TMS) derivatives] revealed that no branched sugars were formed and glucose constituted about 90% of the reaction mixture. It should be noted that analysis—gas chromatography-mass spectrometry (gc-ms) of the corresponding alditol acetates—of the mixtures obtained in the formose reaction carried out under normal conditions revealed the presence of 33-37 components. ... 

Figure 8-4. Methylation analysis of in vitro P-D-glucans. (a) Gas chromatography of the permethyl-ated alditol acetate obtained from methylation analysis of the cellulose synthesized in vitro by the enzyme from blackberry. Peak 1, derivative characteristic of (1 4) linked glucosyl units. Peak 2, internal standard (mj o-inositol). The derivative characteristic of (1 3) linked glucosyl units usually elutes 1 min before the major derivative visible in the chromatogram (not shown see Bulone et al. 1995). (b) Structural characterization by electron impact mass spectrometry of the 1,4,5-tri-0-acetyl-2,3,6-tri-0-methyl-D-glucitol derivative corresponding to peak 1 in A and characteristic of (1 4) linked glucosyl units.

The distribution of substituents in ethylcellulose has been determined by hydrolysis and conversion to the alditol acetates which were determined quantitatively by g.l.c. ° Reference ethyl ethers of D-glucose were synthesized and isolated from a hydrolysate of ethylcellulose of high degree of substitution, and the conformation of these derivatives determined by mass spectrometry. The ratio of ethylation on 0-2,0-3, and 0-6 was found to be 7.45 1 1.5. 

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