School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0440, United States.
J Agric Food Chem. 2011 Dec 28;59(24):12910-6. doi: 10.1021/jf202701b. Epub 2011 Dec 5.
Milled wood lignin samples from Loblolly pine stem wood, forest residue, and bark were isolated and characterized by quantitative (13)C and (31)P nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC) for molecular weight determination. Results from (13)C NMR show the stem wood and forest residue samples have similar functional group contents. However, the bark has fewer methoxyl groups, β-O-4 structures, dibenzodioxocin, and side chains than the other two lignins. The bark lignin has the highest amounts of p-hydroxyphenyl (h) and C-5 condensed lignin, stem wood has the lowest, and the residue lies between. (31)P NMR analysis indicates that bark lignin contains more C-5 substituted phenolics and fewer aliphatic hydroxyl groups than the lignin isolated from stem wood or residue. The molecular weight distribution analysis indicates the bark lignin has higher weight-average molecular weight (M(w)) and polydispersity index than the lignin recovered from stem wood or residue.
从火炬松原木、林分剩余物和树皮中分离出磨木木质素样品，并通过定量（13）C 和（31）P 核磁共振（NMR）、傅里叶变换红外光谱（FT-IR）和凝胶渗透色谱（GPC）进行了表征，以确定分子量。13C NMR 的结果表明，原木和林分剩余物样品具有相似的官能团含量。然而，树皮中的甲氧基、β-O-4 结构、二苯并二恶烷和侧链比其他两种木质素少。树皮木质素具有最高的对羟苯基（h）和 C-5 缩合木质素含量，原木木质素最低，而剩余物则介于两者之间。31P NMR 分析表明，与从原木或剩余物中分离出的木质素相比，树皮木质素含有更多的 C-5 取代酚类和较少的脂肪族羟基。分子量分布分析表明，与从原木或剩余物中回收的木质素相比，树皮木质素具有更高的重均分子量（Mw）和多分散指数。
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