Pyrolysis mass spectrometry and pyrolysis gas chromatography-mass spectrometry of ester- and ether-linked phenolic acids in coastal bermudagrass cell walls

Coastal bermudagrass cell walls were treated with 2 M NaOH at room temperature and subsequently with 4 M NaOH at 170° to determine the amounts of esterified and etherified phenolic acids, respectively. In addition, total phenolic acids were determined by direct treatment of the cell walls with the 4 M treatment. Treatment with 2 M NaOH removed ester-linked p-coumaric, ferulic, truxillic and truxinic acids. Further treatment of the cell wall residue with 4 M NaOH at elevated temperature removed ether-linked phenolic acids. Pyrolytic methylation gas chromatography-mass spectrometry of the residue after 2 M NaOH treatment showed the presence of a small amount of etherlinked truxillic and truxinic acids. Data from the sequential sodium hydroxide and direct 4 M sodium hydroxide treatments showed that a total of 13.3% of the p-coumaric acid and 45.4% of the ferulic acid was ether-linked. A substantial portion of these ether-linked acids was present as a base-soluble fraction of the 2 M treatment.