Abstract
Klason lignin is the most commonly used method of lignin content determination. However, it is time-consuming and consists of acid-insoluble and acid-soluble lignin fractions, resulting in potential errors during handling and calculations. This study investigated the use of a one-step UV-spectroscopy-based acetyl bromide method as a possible alternative. Four Angiosperms; sugar maple, willow, Miscanthus and wheat straw, suggested for use in biorefineries, were analyzed before and after hot-water extraction; autohydrolytic pretreatment. Different organic solvents were evaluated for removal of extractives prior to lignin analyses. Milled wood lignin (MWL) was prepared for each species to calibrate absorptivity used in the acetyl bromide lignin calculations. These studies demonstrated that the acetyl bromide method is reliable and may serve as an alternative to Klason lignin. The acetyl bromide lignin results corroborate well the Klason lignin results and the correlation is improved if the absorptivity determined on respective MWLs is used in calculations.