The analytical pyrolysis of carbohydrates. 2—differentiation of homopolyhexoses according to their linkage type, by pyrolysis-mass spectrometry and pyrolysis-gas chromatography/mass spectrometry

Abstract

Curiepoint pyrolysis (Py)-mass spectrometry (14 eV electron impact) in various modes of operation and Curiepoint pyrolysis-gas chromatograpy/mass spectrometry (Py-GC/MS) afforded discrimination between homopolyhexoses of different glycosidic linkage type and configuration: (1 → 2)-β-, (1 → 3)-β-, (1 → 4)-α-, (1 → 4)-β-, (1 → 6)-α, (1 → 6)-β-glucan and (1 → 2)-α-mannan. Pyrolysis-mass spectrometry in multichannel averaging mode, combined with discriminant analysis data processing, revealed significant discrimination between all polyhexoses, except for the (1→6) linked polymers. By using preheated telescopic glass tube sample holders, additional specificity of the pyrolysis-mass spectral fingerprint for the (1 → 3) linked carbohydrate was obtained. Pyrolysis-mass spectrometry in time-resolved mode yielded ion profiles, especially characteristic for the (1 → 3)-β-glucan. Py-GC/MS was an additional discriminating dimension (retention time), providing structural information about the pyrolysate constituents, in particular concerning the anhydrohexoses.