2.3.4. Fatty acid composition
The chloroform phase of the Bligh and Dyer (B&D) extract at day 0 was evaporated under nitrogen, the lipid phase dissolved in hexane (1 mL), and methylated with 0.5M methanolic KOH (100 mL) for 10 min. The upper layer was analysed for fatty acid methyl esters (FAME) in a gas chromatograph (Agilent 7890A) equipped with a DB-23 column (60 m 0.32 mm, 0.25 mm film thickness) and a flame ionisation detector. Helium was used as the carrier gas. The oven temperature was programmed at 50 C for the first 7 min and increased up to 200 C at a rate of 25 C/min; the temperature was further increased to 230 C at a rate of 3 C/min and held for 26 min. Injection and detector temperatures were 250 C and 280 C,respectively. One microlitre of hexane extract was injected in split mode (25:1), and FAME's identified from standard's retention times (37 FAME's mix, Supelco, SigmaeAldrich).