METHOD OF DETERMINING LIGNIN Russian patent published in 2014 - IPC D21C3/02 G01N33/46 G01N21/27 

FIELD: chemistry.

SUBSTANCE: method comprises mixing lignocellulose material with an aqueous dioxane solution which is obtained by mixing concentrated nitric acid and 1,4-dioxane in ratio of 1:4 (by volume), heating the reaction mixture on a boiling water bath for 15 minutes, adding 2 M sodium hydroxide solution, adjusting the volume of the reaction mixture with distilled water and filtering, measuring optical density of the filtrate at 440 nm and determining content of lignin in the cellulose semiproduct based on the value of optical density.

EFFECT: simpler and faster analysis.

2 tbl, 24 ex