Natural Resources

Categories: Natural Resources
Origin: CSA
Close date: Jul 17, 2021
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This Standard describes a method for the quantification of the aliphatic (R–OH), phenolic (Ph–OH) and carboxylic acid (R–COOH) hydroxyl groups present in lignin. Phenolic hydroxyl groups include: syringyl (S), guaiacyl (G), p-hydroxyphenyl (H) units and condensed phenolics incorporating β-5, 4-O-5’ and 5-5’ inter-unit linkages.

The procedure utilizes derivatization with a phosphorus-containing reagent followed by 31P NMR analysis.

This procedure is applicable to dry solid lignins (for example in powdered form) isolated from the pulping processes in their acid form, and that are completely soluble in the NMR solvent mixture, otherwise data represent only the structure of the soluble portion of lignin.

It does not apply to raw black liquor, wet lignin, nor lignin with a high ash or carbohydrate content to the extent that these affect lignin solubility in the selected solvent system.