Anisole-based assessment for the quantification of methoxyl groups in lignin-rich biomass

The methoxyl group (-OCH3) is abundant in biomass containing lignin. The quantification and biogeochemical evolution features of -OCH3 in these materials are still a research focus. The quantification methods of -OCH3 available up to date overall have a large error range and/or are time consuming through the need for a series of treatments. The present work reports an anisole-based assessment method for -OCH3 quantification in biomass containing lignin, by applying an anisole standard reagent to react with hydroiodic acid to create an external quantification curve used for -OCH3 quantification in samples studied. In practice, 10-200 mu L of anisole and 0.2-1 g of lignite samples were reacted with surplus hydroiodic acid under 130 celcius for 30 min to quantitatively obtain the iodomethane (CH3I) produced in a 20 mL ampere vial. The headspace gas was subjected to GC-FID analysis to create an external calibration curve for -OCH3 quantification in the lignite samples. The results indicated that the external calibration curve had a fairly good correlative relationship (R-2 = 0.9523). Quantification of -OCH3 carbon in lignites by this method is well within the scope of previous reports. It seems likely that this simple and precise quantification method will have promising applications for methoxyl group quantification in lignin-rich biomass.