Pyrolysis study of pectin by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry

Abstract

The thermal decomposition of pectin was studied, and some major products were online analyzed by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The principal products were furfural, methyl 2-furoate and 5-oxo-tetrahydro-furan-2-carbaldehyde. Some new high molecular weight intermediate products were firstly observed thanks to the soft ionization and MSMS structural analysis of ions. The results demonstrated the variation of the pyrolysis product pool with temperatures, dividing the thermal decomposition process into two stages: the low-temperature stage for the intramolecular pyrolysis of galacturonic acid subunit at the chain ends of polymers and the high-temperature stage for the rupture of α-(1 → 4) glycosidic bond between galacturonic acid subunit. This work reported a new application of SVUV-PIMS in pectin pyrolysis and demonstrated its good performance in product analysis. The formation mechanisms of some major products from pectin pyrolysis were discussed based on the analysis of pyrolysates, which should provide insight into the pyrolysis behavior of pectin.