2.6. Preparation of extracts for analysis
The extracts (1 cm3) of different concentrations were evaporated to dryness with rotary vacuum evaporators at room temperature and the residues were dissolved in a mobile phase (acetonitrile:methanol:ethyl acetate, 6:2:2, v/v) to a concentration of 1 mg/cm3. Extracts were filtered through a 0.45 _m Millipore filter before HPLC analysis.