Different types of hydroxyl groups are among important lignin functionalities affecting lignin reactivity in lignocellulosic processing and commercial utilization. This paper compares the most popular quantitative NMR techniques in functional lignin analysis (13C, 31P and 1H NMR methods). The inaccuracies of currently used protocols have been demonstrated and appropriate modifications in the analytical procedures are suggested. The modified methods have been comprehensively compared using a large number of different native and technical lignins, including widely used lignin standard preparations. Good correlation has been found between the modified protocols in the quantification of various types of phenolic and aliphatic OH groups. However, the difference in the quantification of lignin carboxyl groups is still significant. Advantages and limitations of each method are discussed and an optimal approach is suggested.

Analysis of lignin hydroxyl groups by NMR spectroscopy

249th National Meeting (2015)

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Analysis of lignin hydroxyl groups by NMR spectroscopy<br />