A 13C CP/MAS-Based Nondegradative Method for Lignin Content Analysis

Abstract

Most current lignin content analysis methods require dissociation/degradation and/or preconditioning steps. A simple yet reliable method that can be used to analyze content of various lignocellulosic biomasses without destroying their native structure is needed. In this research effort, an improved nondegradative method for determining the content of lignin in native biomass was established. By extending the scope of the solid state 13C CP/MAS NMR technique, via homogeneous mixing of an internal standard (TMSP) with varying lignin contents, a standard curve was generated for calculating the lignin content of various biomasses without dissociation or degradation. The results showed good accuracy in the calculation of lignin content. Compared to chemical degradative methods, such as the acetyl bromide method, the relative difference was less than 5.00%. This method is applicable for estimating lignin content in certain samples (e.g., acid insoluble lignin) that are difficult to analyze accurately with chemical methods. By offering an alternative methodology for lignin content estimation using solid state 13C CP/MAS NMR with an internal standard, this study also demonstrated the quantitative potential of solid state 13C CP/MAS NMR when coupled with the internal standard (TMSP). The proposed procedure fills a current technological gap in lignocellulosic biomass analysis.