Color Reaction with Quinone Monochlorimide

Wood meal (3 mg) is suspended in 2 ml of ethanol, and 0.2 ml of an ethanolic solution of quinone monochlorimide (1 mg) and 1ml of an 0.04 M sodium hydroxide solution are added. The suspension is shaken for lh at room temperature. After removing the solution by filtration, the residual wood is washed with ethanol, and the blue color which forms is recorded while the material is still wet with ethanol. 

For an isolated lignin, a 20-mg sample is dissolved in 50ml of ethanol or methyl cellosolve. To 2 ml of this solution are added the same amounts of quinone monochlorimide and sodium hydroxide as were used in the above procedure. The solution is allowed to stand for 1 h at room temperature. Two ml of the solution is diluted to 25 ml with methyl cellosolve or ethanol and the absorption spectrum (/max 640 nm) is recorded spectrophotometrically. 

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