Xylans, acetates fractionation

Blake and Richards26 carefully examined all of the steps involved in the analysis of complex polysaccharides, and preferred to use the alditol acetates in studies on the classification,428 fractionation,427 and molecular aggregation428 of hemicelluloses and speargrass xylan.420,430... 

Before discussing the various derivatives that have been used, it should be remembered that oligosaccharides are often obtained by chromatography on paper or on cellulose columns, and this may cause them to become contaminated by xylan this may be eliminated by extraction of the crude fractions with hot ethanol.474 For similar reasons, glucose that is really extraneous may be detected in fractions separated by electrophoresis on cellulose acetate.475 Gas-liquid chromatography was used to show the presence in pituitary glyco-... 

In the case of water-soluble O-acetylated xylans and glucomannans, an ammonium acetate solution with a pH of 7 was employed as eluent in connection with the SEC separation step (7). However, for dkali extracted xylans and glucomannans, a more alkaline (pH 13) sodium hydroxide/acetate eluent was required (3). In all cases pretreatment of the SEC fractions by passage through a cation-exchange resin prior to MALDI-MS analysis and/or the use of MALDI probes coated with a Nafion film (2), were necessary in order to minimize the disturbance by buffer ions during the MALDI analysis step. 

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