Preferred Method for Isolation and Purification of Lignin

In the selection of starting material, one should be aware that there may be a variation in lignin composition depending on the part of a tree from which the wood is taken. Therefore, sapwood free of reaction wood should be used for the preparation of a reference lignin from a particular species. Size reduction and removal of extractives from the wood can be accomplished according to the directions given by Bjorkman (1956). 

The wood sample (dried in vacuo over P205) is suspended in toluene (purified by distilling over sodium) and milled in a modified National Bureau of Standards 

Springer Series in Wood Science Methods in Lignin Chemistry (Edited by S.Y. Lin and C.W. Dence) 

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