The liquid phase was filtered with 0.5-μm holes for purification and kept at -20℃ until analysis. The extract (1μL) was subjected to a QP-5000 GC–MS system (Shimadzu Co.) by electron impact ionization at 70 eV. GC separation was performed on a column (0.25 mm i.d×30m) of HP-5MS (Hewlett Packard) by the splitless injection method at 120℃.