Analytical pyrolysis - A tool for revealing of lignin structure-antioxidant activity relationship

Systematic and thorough investigation of the structure and antioxidant properties of different technical lignins, high molecular polyphenols of natural origin, which are formed in large amounts as by-product of pulp-and-paper industry and other lignocellulosics chemical processing, was made. Py-GC/MS was the main method used to quantitatively determine the structural descriptors needed for rationalization of lignin antioxidant activity. Size-exclusion chromatography (SEC), electron paramagnetic resonance (EPR) spectroscopy and wet chemistry tests were also used as complementary methods. Antioxidant properties of lignin samples under study were evaluated as their capacity to scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. The use of Py-GC/MS in combination with some other experimental and chemometric methods allowed for the first time quantitatively characterize lignin structure-antioxidant activity relationship, which can significantly favor the rational use of lignin.