The resulting methyl esters recovered in the hexane layer were analyzed with a gas chromatograph (GC–MSQP2010S, Shimadzu, Japan) equipped with a TRB-5MS capillary column (30 m 0.25 mm 0.25 lm) at 70 eV (m/z 40–400; source at 250 oC and quadruple at 100 oC) in the EI mode.