Characterization of neutral sugars and uronic acids after methanolysis and trimethylsilylation for recognition of plant gums

The main standard neutral sugars and uronic acids that occur as components of plant gums were methanolysed and silylated for study by gas chromatography-electron impact and chemical ionization mass spectrometry (GC-EI-MS and GC-CI-MS). The 25 TMSi methylglycosides, components of the chromatograms obtained were studied and identified by their mass spectra and/or comparison with the corresponding standards. In addition, an unusual uronic acid (4-O-methylglucuronic acid) and the lactone forms of glucuronic acid are reported. A classification of the ions in both EI-MS and CI-MS which allows differentiation between sugar classes and their tautomeric forms is given, The sample preparation method and the results of the above identification were applied to the analysis of some plant gums and a seventeenth century ink sample.