Behavior of phenolic substances in the decaying process of plants: I. Identification and Quantitative Determination of Phenolic Acids in Rice Straw and Its Decayed Product by Gas Chromatography

Phenolic acids in rice straw and its decayed product were surveyed and quantitatively analyzed by gas chromatography.

1) Thirteen kinds of phenolic acids in rice straw and its decayed product were identified. Besides p-hydroxybenzoic, vanillic, P-coumaric, and ferulic acids which had been already reported, nine phenolic acids were newly identified; these were benzoic, salicylic, syringic, protocatechuic, β-resorcylic, caffeic, sinapic, gallic, and gentisic acids.

2) A gas chromatographic analysis was applied to the micro-determination of major phenolic acids in rice straw and . the decayed products. The methanolic alkaline extracts from them were washed with ether, acidified, transferred into ether, trimethylsilylated, and injected into a gas chromatograph equipped with a silicon SE-30 column. The recoveries of p-coumaric, p-hydroxybenzoic, vanillic, and syringic acids were more than 90%, and ferulic and syringic acids were recovered at about 70%.

3) The content of each of the above described major phenolic acids in rice straw ranged from 0.002 to 0.037% per dry weight. p-Coumaric acid was contained in the largest amount. Ferulic and vanillic acids followed. In the decayed straw, these contents decreased to 0.002–0.017%. The whole phenolic substances in ether-extracted fraction were present at 0.34%, and the amount decreased to one-third during the decaying process.