High-performance liquid chromatographic methods for quantitative assessment of degradation products and extractives in pretreated lignocellulose.

Long-term economic, national security, and environmental concerns have motivated research into renewable fuels from lignocellulosic biomass. Among energy alternatives, biomass-derived ethanol represents one of the more promising commodities for long-term sustainability of transportation fuels. Herbaceous agricultural residues, such as corn stover, represent a major source of lignocellulosic material with considerable potential for use in biomass-to-ethanol schemes. Currently, the technology for conversion of biomass to ethanol involves dilute acid pretreatment of lignocellulosic materials, followed by enzymatic hydrolysis of cellulose and fermentation of monomeric sugars to produce ethanol. However, a variety of degradation products are produced upon dilute acid pretreatment of lignocellulosic biomass, which exert an inhibitory effect on downstream fermentation processes and reduce bioethanol conversion. Thus there is increased the demand for reliable analytical methods to advance a more understanding of lignocellulose pretreatment. Several liquid chromatographic methods are developed for a systematic analysis of various degradation products. High-performance liquid chromatography is the most widely used analytical separation technique, because of its reproducibility, sensitivity, and suitability for separating nonvolatile species, which makes the method ready for accurate quantitative determinations. A reversed-phase HPLC method with UV detection is developed for simultaneous separation and quantitation of organic acids and neutral degradation products present in the corn stover hydrolysate. On the other hand, inorganic ions and some organic anions which present in water extractive from corn stover are separated and quantitated by the developed ion chromatographic method with conductivity mode. Sugars and alditols are determined using high-performance anion chromatography with pulsed amperometric detection.