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

Abstract

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 13 C-labeled lignocellulose from corn ( Zea mays ) collected with a dephasing time of 1/2ν MAS, the chemical shifts of β- d -xylopyranose (Xyl p ) and α- l -arabinofuranose (Ara f ) in glucuronoarabinoxylan, the major hemicellulose in the secondary cell walls of the gramineous plant, were assigned.