Alditol acetates, chromatogram

Adsorption surface, SFC, solvent Interactions, 1>>9 Air monitors. Industrial chromatography, 200 Alditol acetates, chromatogram, 32f Alkyl groups, bonded, HPLC development, 82,83 Amides, enantiomeric, separation, >l3,>l>lf Amine compounds, RPLC, 8>l Amino acids HPLC, 86,87f Ion exchange, 81 ligand exchange, >>... 

Although many analyses are performed on alditol acetates (see Section VII, p. 56), in order to avoid the formation of multiple peaks, such a reduction is not practical when the mixture contains ketoses, notably fructose. Such analyses are mainly encountered with medical samples and in the examination of sugars occurring free in Nature. Furthermore, the peak-area ratios may be used as a means of identification, to check on the completeness of trimethylsilylation,67,89 and, despite the complex chromatograms obtained from trimethyl-silyl derivatives, they have the merit of being rapidly formed.89 For all of these reasons, improvements in the separation of monosaccharides as their trimethylsilyl derivatives continue to be of considerable importance. 

The amount of each neutral monosaccharide in the samples can be calculated relative to the internal standard, allose, using response factors. The relative response of the detector for the individual alditol acetates can be calculated from the areas under the peaks for each alditol acetate, relative to the area under the peak for allitol acetate. There should be no peaks in the chromatogram of the water control and only one peak, corresponding to allitol hexaacetate from the internal standard allose, in the chromatogram of the TFA control. 

Figure 9. Open tubular gas chromatogram of partially methylated alditol acetates obtained from blood-group A active tetraglycosylceramide (A) and hexaglycosyl-ceramide (B), respectively. Stationary phase was OV-1, and carrier gas was Ns. Column temperature was kept at 175°C for 14 min, then raised l°C/min. The designation above the peaks indicate actual binding positions.

Figure 11 GC/MS assay of alditol hexa-acetates quantified against inositol internal standard (IS), (a) In the chromatogram shown here the monosaccharides making up a plant cell wall are being quantified as their alditol acetates, using inositol (Ino) as the (IS). The GC separation of these reduced sugars is essential for their identification. The mass spectra of the alditol acetates of the hexoses, glucose (Glc) (b), galactose (Gal) (c), and mannose (Man), are essentially identical, as are the mass spectra of the alditol acetates of the pentoses, xylose (Xyl) and arabinose (Ara), and the deoxysugars, rhamnose (Rhm) and fucose (Fuc).

Fio. 29. Gas-liquid chromatogram of the alditol acetates produced from a standard mixture of the parent carbohydrates. For GLC conditions see text. Reproduced from Lehnhardt and Winzler (L5) with permission. 

Fia. 30. Gas-liquid chromatograms of the alditol acetates of the neutral sugars released after hydrolysis of various glycoproteins. Arabitol was added as the internal standard. (A) Orosomucoid (B) canine submaxillary mucin (C) a glycopeptide released by the action of trypsin from intact human erythrocytes. For GLC conditions see text. Reproduced from Lehnhardt and Winzier (LS) with permission. 

Fig. 14.—Gas Chromatogram of Formose Alditol Acetates. [Apparatus Hitachi 063 gas chromatograph flame-ionization detector column 200 X 0.3 cm diam. stainless steel, 3% ECNSS-M on Gas Chrom Q (100-200 mesh). Temperature program 90°— 190° at 5°/min. Carrier gas nitrogen at 70 ml/min.]...

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 ... 

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.

An important approach that reduces the number of peaks in the chromatogram involves reduction of sugars to corresponding alditols (Equation 9.10). The alditols are converted to TMS or TFA derivatives prior to chromatography although acetate deriva-... 

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...

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