Determination of Three Kinds of Flavonoids in Scutellaria Baicalensis Purified by Macroporous Absorption Resin

OBJECTIVE To establish a method for determination of the content of baicalin, baicalein and wogonin in Scutellaria baicalensis purified by macroporous absorption resin by HPLC. METHODS The macroporous absorption resin AB-8 was used to separate and purify the total flavonoids in the water extract from Scutellaria baicalensis. The HPLC method was used to determine the content of baicalin, baicalein and wogonin. The analytical column was Agilent TC-C₁₈(4.6 mm×250 mm, 5 μm). The mobile phase was a mixture liquid of acetonitrile and 0.1% phosphoric acid in water by gradient elution. The UV detector wavelength was 280 nm, the flow rate was 1.0 mL·min^-1, and the column temperature was 30 ℃. RESULTS The linear ranges of baicalin, baicalein and wogonin were 0.022 4-0.448 0 μg(r=0.999 9), 0.021 0-0.420 0 μg(r=0.999 9), 0.010 3-0.205 0 μg(r=0.999 9), respectively. The average recoveries of the method for baicalin, baicalein and wogonin were 97.3% with RSD 1.71%, 98.4% with RSD 2.05% and 98.1% with RSD 1.65%, respectively. The average contents of baicalin, baicalein and wogonin in the water extract from Scutellaria baicalensis with macroporous absorption resin were 27.52%, 6.87% and 2.13%, and the average contents were 9.16%, 1.66% and 0.54% without purification. CONCLUSION The method is simple, accurate, sensitive and stable.