The extracts were concentrated under a flow of N2 gas to about 50 mL. 70 mL of mobile phase A was added and centrifuged using a microfilterfuge tube (Rainin Instrument Co. Inc., Emeryville, CA) at 5000 rpm for 30 min in a centrifuge (Metpath, Paterson Scientific Inc., NJ). The resulting solutions were transferred to 0.5mL amber autosampler vials to prevent photodegradation of TCs and SAs.