A facile spectroscopic method for measuring lignin content in lignocellulosic biomass

摘要

Although measuring lignin contents is a routine operation for biomass compositional analysis in process development aiming at efficient utilization of woody biomass, it is still a challenging task requiring many steps, hazardous reagents, heating, and a significant time. A facile spectroscopic method, our CASA (Cysteine-Assisted Sulfuric Acid) method, was developed to quantify the lignin content of lignocellulosic biomass, based on an extraordinary system in which biomass samples are fully dissolved in 72% H2SO4 containing cysteine at 24 degrees C in 60 min. Using synthetic lignins, the lignin absorptivities were determined to be 17.25 g(-1) L cm(-1) for softwood lignin and 11.23 g(-1) L cm(-1) for hardwood lignin and monocot lignin. Seven softwoods, six hardwoods, and six monocots were tested using the CASA method. A high coefficient of determination (R-2 = 0.95) was found between the CASA results and the acid-insoluble lignin contents, and an even better R-2 (0.98) was obtained when the CASA data were correlated with the total lignin contents.

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