Evaluation of guaiacyl lignin aromatic structures using 13CO2administered Ginkgo biloba L. xylem by quantitative solid- and liquid-state 13C NMR

Abstract

Ginkgo biloba L. saplings were cultivated in an airtight growth chamber with 13CO2 for two months. The 13C ratio of the newly developed xylem region was ca. 85%, evaluated by high lateral resolution secondary ion mass spectrometry and thioacidolysis/GC-MS. Quantitative solid-state 13C direct polarisation/magic angle spinning (DP/MAS) NMR measurements with high-speed MAS of 70.0 kHz were conducted for cutting-milled wood (CMW), ball-milled wood (BMW), and enzymatically saccharified lignin (EL) samples. In addition, quantitative liquid-state 13C NMR measurements were carried out for EL in DMSO-d 6. Major lignin aromatic signals were classified into three groups of aromatic carbons of C-H, C-C, and C-O, and their area ratio was compared within these measurements. EL samples in solid- and liquid-state showed nearly the same results. However, the results for CMW and BMW in solid-state NMR suggest the structural alteration of lignin within the sample preparation procedure, including ball milling.