Y-H Percival Zhang, Lee R. Lynd*
Thayer School of Engineering
Dartmouth College
Hanover, NH 03755
Phone: (603)646-3496
Fax: (603)646-3856
Email: Percival.zhang@dartmouth.edu, Lee.lynd@dartmouth.edu
Quantitative saccharification (QS) of lignocellulose is a basic technique used to analyze the composition of lignocellulosic materials. We undertook to modify the standard QS protocol in order to improve the precision of xylan determination. We found that xylose degradation during primary hydrolysis was reduced by at least 2-fold when hydrolysis was carried out using 69% (w/w) sulfuric acid as compared to using 72% sulfuric acid, as specified in the standard protocol.
Using standard conditions for secondary hydrolysis (4 % sulfuric acid), xylose degradation was 13%. However, lowering the sulfuric acid concentration to 1% was still sufficient to achieve complete hydrolysis of soluble xylan oligomers but resulted in 3% loss of xylose in a degradation control. Since at least 3% sulfuric acid is required to get complete hydrolysis of soluble cellodextrins, our revised procedure involves determination of glucan and xylan separately. Using the revised protocol, xylan mass fractions in corn stover, bagasse, and yellow poplar were about 5% lower than measured using the standard protocol. It is believed that calculating xylan using a correction based on a xylose control results in overestimation of xylan content because xylan is less susceptible to degradation than is xylose. The revised protocol is believed to allow more accurate determination of biomass composition with little added effort.