Structural analysis for lignin characteristics in biomass straw

• The studies on lignin could be divided into qualitative and quantitative analyses.
• Quantitative and qualitative analyses of lignin provide in depth microstructure interpretation for biomass optimisation.
• Sensitive quantitative HSQC techniques are the most diagnostic and accurate tools to investigate lignin structure.
• The most accurate way to study the straw lignin is to use a combination of several techniques for complimentary data.

Agricultural by-products are the most promising feedstock for the generation of renewable, carbon neutral substitutes for synthetic materials (e.g. biofuel, building materials). The demand for efficient utilisation of lignin biomass has induced detailed analyses of its fundamental chemical structures and development of analysing technologies. This paper reviews the structural analysis techniques for straw lignin together with the morphology of the lignin biomass and the study of the form and structure of organisms and their specific structural features. The review showed that the studies on lignin could be divided into the qualitative and quantitative analyses; different analytical methods could provide significantly different results that are even sometimes not directly comparable. Among many techniques reviewed, the magnetic resonance techniques have proved to be efficient analytical tools for the structural elucidation of these complex biopolymers. Quantitative and qualitative structural analysis of lignin indicated a great potential for industrial crops optimisation due to in-depth microstructure interpretation, and detailed and accurate chemical composition although the composition and structure of straw lignin have been discovered highly complex and varied considerably within and among plants. The structure of lignin has remained one of the most difficult biopolymers to characterise, however recent advances in analytical chemistry and spectroscopy have dramatically improved the understanding of this natural resource, and further value added utilisations are being expected for the lignin and its related biomass.