Lignin, an aromatic biopolymer, in the terrestrial lignocellulosic biomass constitutes the single largest and sustainable source of biofuels and biochemicals. The recalcitrant nature of lignin is a hindrance to its chemical or biochemical conversion. Moreover, its insolubility in water too is a major challenge in its quantification which is a necessary step prior to and after its conversion. Though there are celebrated quantification methods like the classical Klason lignin method and the acetyl bromide solubilisation (ABSL) method they are not environmentally friendly as harmful chemicals are used in these processes. State of the art analytical techniques based on NMR, HPLC and GC-MS are also being developed for the quantification of lignin owing to the strategic significance of its detection and estimation. Addressing these issues, herein we report a simple and environmentally friendly method for the quantification of lignin (alkali, low sulfonate content) in a two-step process using water as the solvent for the solubilisation of lignin, which is indeed a breakthrough. Clear aqueous solutions of lignin were obtained by high-speed stirring using an ultra-turrax. The aqueous solutions of lignin showed characteristic absorbance at 306 nm. A linear relationship between the amount of lignin and the absorbance at 306 nm is observed that formed the basis of this novel analytical method for the quantification of lignin.

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