This product is an extract made from the dried roots of Scutellaria baicalensis Georgi, a plant in the Lamiaceae family, through processing.  

【Preparation】Take Scutellaria baicalensis, decoct with water, combine the decoctions, concentrate to an appropriate amount, adjust the pH to 1.0–2.0, maintain at 80°C, allow to stand, and filter. Mix the precipitate with an appropriate amount of water, adjust the pH to 7.0 with a 40% hydrogen solution, add an equal amount of ethanol, stir to dissolve, and filter. Adjust the pH of the filtrate to 1.0–2.0, maintain at 60°C, allow to stand, and filter. Wash the precipitate successively with an appropriate amount of water and ethanol of different concentrations until the pH reaches 7.0, evaporate to remove ethanol, and dry under reduced pressure to obtain the product. 

 【Characteristics】This product is a light yellow to brownish-yellow powder; taste bland and slightly bitter. 

 【Identification】Take 1 mg of the product, add 1 ml of methanol to dissolve, and use as the test solution. Separately, take baicalin reference substance, add methanol to prepare a solution containing 1 mg per 1 ml, and use as the reference solution. Carry out the test as described under Thin-Layer Chromatography (General Rule 0502). Apply 2 μl of each of the above two solutions to the same poly film, use as the developing solvent, develop, remove, air-dry, and examine under ultraviolet light (365 nm). The chromatogram of the test solution shows a fluorescent spot at the same position as the chromatogram of the reference solution, with the same color. 

 【Inspection】Moisture: Not more than 5.0% (General Rule 0832, Method 2).

 Residue on ignition: Not more than 0.8% (General Rule 0841). 

 Heavy metals: Take the residue from the residue on ignition test, examine according to the law (General Rule 0821, Method 2), not more than 20 mg/kg.

【Assay】Determine by High-Performance Liquid Chromatography (General Rule 0512). Chromatographic conditions and system suitability test: Use octadecylsilane-bonded silica gel as the filler, methanol-water-phosphoric acid (47:53:0.2) as the mobile phase; detection wavelength is 280 nm. The theoretical plate number calculated for the baicalin peak should not be less than 2500. Preparation of reference solution: Take an appropriate amount of baicalin reference substance, accurately weighed, add methanol to prepare a solution containing 60 μg per 1 ml. Preparation of test solution: Take about 10 mg of the product, accurately weighed, place in a 25 ml volumetric flask, add an appropriate amount of methanol to dissolve, then add methanol to volume, and mix well. Precisely measure 5 ml, place in a 25 ml volumetric flask, add methanol to volume, mix well, filter, and use the successive filtrate. Assay method: Precisely inject 10 μl each of the reference solution and the test solution into the liquid chromatograph, determine, and calculate. This product, calculated on the dried basis, contains not less than 85.0% of baicalin (C21H18O11). 【Storage】Keep sealed, store in a cool and dry place.