The structure of p-coumaric acid and coniferyl aldehyde were founded both in residual lignin and in dissolved lignin, so resudial lignin and dissoled lignin both contained carbonyl.

• 残余木素和溶出木素中都发现存在对香豆酸和松柏醛结构，导致残余木素和溶出木素都中含有羰基；