Py-SPME-GC-MS with on-fiber derivatization as a new solvent-less technique for the study of polar macromolecules: Application to natural gums

Off-line pyrolysis coupled with GC-MS through SPME sampling, overcomes some of the limitation of online Py-GC-MS configuration without laborious sample treatment. The introduction of on fiber silylation procedure between SPME sampling and analysis allowed to obtain a complete silylation of polar pyrolysis products with diagnostic relevance. The method was applied to the analysis of pure sugars and carbohydrates, providing a picture of the type of anhydrosugars evolved by pyrolysis of natural gums, namely cellulose and polysaccharide based gums (Arabic, Ghatti, Tragacanth, Guar, Karaya and Xanthan). Characteristic anhydrosugars produced by pyrolysis of hexoses, pentoses and deoxyhexoses were tentatively identified. Despite an unambiguous marker for uronic acids was not identified, the final method allowed to obtain, with minimal work-up, a detailed picture of polar pyrolysis products as those obtainable from carbohydrates, which can be easily used for identification purposes.