Methodological Aspects of the Determination of Fatty Acids in Soil by Thermochemolysis

• Published in: Eurasian soil science 2021-08, Vol.54 (8), p.1176-1182
• Main Authors: Farkhodov, Yu. R., Yaroslavtseva, N. V., Kholodov, V. A.
• Format: Article
• Language: English
• Subjects: Acidic soils; Amino acids; Analysis; Composition; Earth and Environmental Science; Earth Sciences; Esters; Fatty acid methyl esters; Fatty acids; Geotechnical Engineering & Applied Earth Sciences; Hydroxides; Microbiomes; Organic matter; Organic soils; Pyrolysis; Relative abundance; Soil; Soil Chemistry; Soil microorganisms; Soil organic matter; Soil structure; Soil temperature; Soils; Temperature; Yields
• ISSN: 1064-2293; 1556-195X
• DOI: 10.1134/S1064229321080068

Fatty acids (FAs) are among the most informative parts of nonspecific soil organic matter). Their composition and content reflect the specific features of many soil processes and the structure of the soil microbiome. One of the simplest and fastest methods to analyze FAs is thermochemolysis. Thermochemolysis is widely used to assess the content and composition of soil FAs but has many insufficiently clarified methodological issues. The goal of our work is to study the influence of various conditions of thermochemolysis on the detected FA composition by the case study of typical chernozem. The yield of fatty acid methyl esters (FAMEs) depending on the concentration of the methylating agent tetramethylammonium hydroxide (TMAH) is estimated as well as the pyrolysis temperature and the time of soil exposure to TMAH. It is shown that an excessive amount of the derivatizing agent at high pyrolysis temperature decreases the yield of FAMEs and the relative abundance of monounsaturated FAMEs. The optimal conditions for assaying the FA content are the temperature range of 300–500°C and 15–40 mmol/g C TMAH. It is shown that the time of soil exposure to TMAH before analysis has no effect on the results of thermochemolysis.