One-step lipid extraction and fatty acid methyl esters preparation from fresh plant tissues

A procedure for the digestion of fresh tissue, transmethylation of lipids, and the extraction of fatty acid methyl esters (FAMES) in one step is described. Fresh tissues or isolated lipids are heated with a reagent containing methanol:heptane:benzene:2,2-dimethoxypropane:H2SO4 (37:36:20:5:2, by vol), methanol:heptane:toluene:2,2-dimethoxypropane:H2SO4 (39:34:20:5:2, by vol), or methanol:heptane:tetrahydrofuran:2,2-dimethoxypropane:H2SO4 (31:42:20:5:2; by vol). At 80 degrees C the simultaneous digestion and lipid transmethylation takes place in a single phase. After cooling at room temperature two phases are formed; the upper one contains the FAMES ready for GLC analysis. The procedure allows the determination of the fatty acid composition of lipids from tissues containing high proportions of triacylglycerols (oil seeds), water (leaves), or both (oil fruits). Due to the complete extraction of the lipids from the tissue, their content can be determined by adding an internal standard to the sample.