ABSTRACT High‐resolution NMR analysis of heterogeneous, insoluble lignocellulosic materials is a significant challenge because poor magnetic field homogeneity and restricted molecular mobility often hinder the acquisition of reproducible solution‐state NMR spectra. In studies of lignocellulosic biomass and plant cell walls, gel‐state NMR methods have enabled important advances. However, practical limitations in sample preparation, shimming stability, and spectral broadening have constrained method robustness and routine use. Here, we present a finely pulverized low‐moisture (FPL) gel‐state NMR method that enables the reliable acquisition of high‐quality two‐dimensional (2D) HSQC spectra from intact whole plant cell walls without chemical pretreatment. Systematic evaluation of drying protocols, ball‐milling efficiency, and solvent composition shows that moisture control and particle fineness are the primary factors influencing gel homogeneity and magnetic field shimming performance. Use of a DMSO‐ d 6 /DMF‐ d 7 (4:1, v/v) solvent system produces gels with reproducible chemical shifts, narrow linewidths, and well‐resolved heteronuclear correlations. This stability allows standard automated shimming and acquisition protocols to be applied reliably. The method is validated across diverse types of biomass, establishing a robust NMR sample‐preparation framework for whole plant cell wall analysis and extending the practical reach of solution‐state NMR methodologies.
Kim et al. (Thu,) studied this question.