A method of detecting and determining lignin compounds in mortars and concretes

Lignosulphonate and Vinsol-resin type admixtures in concrete are oxidized by precipitated manganese dioxide in caustic soda to produce a high yield of vanillin and other carbonyl products. The products with carbonyl groups react with 2–4 dinitrophenylhydrazine to form brightly coloured osazones and hydrazones, which are quantitatively determined with a spectrophotometer.