Soil lipids from accelerated solvent extraction: Influence of temperature and solvent on extract composition

Abstract

Soil lipids are frequently extracted using accelerated solvent extraction as it is reliable and effective. However, comparisons of extraction efficiency with different soil types or different solvents or temperatures are scarce. We extracted lipids from two soil types (vertisol and cambisol) with similar organic matter content and using four solvents or solvent mixtures of different polarity, at different temperatures, to evaluate the influence of these parameters. We compared the quantity of lipid extracted and characterised the extracts from the cambisol by way of gas chromatography–mass spectrometry (GC–MS) to determine the type of components extracted. Each component was quantified and principal component analysis was used to highlight the influence of solvent and temperature.Despite similar organic carbon content, the extracts varied significantly and were dependent on solvent and temperature. The lipid yield was affected differently by the solvent or temperature depending on the soil. GC–MS revealed differences in the composition of the extracts. The principal component analysis showed unambiguously that extraction with a high concentration of MeOH led to extraction of carbohydrates. In addition, temperature might have altered the n-alcohols and sterols, whereas the n-carboxylic acids were more efficiently extracted at higher temperature.