Selective Signal Detection in Solid-State NMR Using Rotor-Synchronized Dipolar Dephasing for the Analysis of Hemicellulose in Lignocellulosic Biomass

Solid-state dipolar dephasing filtered (DDF)-INADEQUATE experiments were used to detect the hemicellulosic signals of lignocellulosic mixtures; here dipolar dephasing was used as a signal filter to remove signals derived from cellulose. The maximum filtering efficiency was obtained when the dephasing time was adjusted to half the rotor period at a magic-angle spinning (MAS) frequency of 12 kHz, which indicated that the molecular motions in hemicelluloses are faster than those in cellulose. In a DDF-INADEQUATE spectrum of uniformly C-13-labeled lignocellulose from corn (Zea mays) collected with a dephasing time of 1/2v(MAS), the chemical shifts of beta-D-xylopyranose (Xylp) and alpha-L-arabinofuranose (Araf) in glucuronoarabinoxylan, the major hemicellulose in the secondary cell walls of the gramineous plant, were assigned.