Humic acid extracted from peat was classified into seven fractions by alcohol precipitation technique for the analysis of thermolysis,flocculation limit and some optical properties.

• 结果表明，酒精沉淀分级法是按分子量大小、缩合程度的高低将胡敏酸分成较均一的级分，而对胡敏酸的性质、结构等无破坏作用。