The Soxhlet extraction conditions were modified on the basis of
Chinese national standard (GB/T 5009.145-, 2003). Ten gram rice
powder was transferred into the Soxhlet thimble and 30 mL methanol
aqueous solution (1:1, v/v) were added into a 50 mL roundbottom
flask. The experiment was performed at 85 C for 3 h. Then
the extract was concentrated to 1.0 mL using a rotary evaporator at
30 C. The concentrated extract was filtered through a 0.45 lm
microporous membrane for subsequent HPLC–MS/MS analysis.
All the extractions were performed at least three times, and the
mean values were reported.