Carry out the method for High performance liquid chromatography (Appendix VI D). 1. Chromatographic conditions and system suitability test Use a column packed with octadecylsilane bonded silica gel and a mixture of methanol-water (73:27) as the mobile phase. Detection wavelengh is 270nm and the number of the theoretical plates of the column is not less than 2000, calculated with the peak of tanshinone IIA . 2. Preparation of reference solution Weigh accurately 10mg of tanshinone IIA RS to a 50ml amber colored volumetric flask, dilute with methanol to volume, and mix well to produce a solution of 20μg per ml. 3. Preparation of test solution Take 10 tablets, with coating removed, accurately weigh, calculate the average weight per tablet, powder and weigh 0.5g of the powder accurately, add 25ml of methanol accurately, weigh, ultrasonic extract for 15 minutes, cool, weigh again and make up the loss, mix well, filter. Discard the primary filtrate,take the successive filtrate as the test solution. 4. Assay Inject 20μl of reference solution and test solution into the column respectively and record their chromatograms and calculate the content by external standard method . Calculation formula is as follows: Where Cs is the concentration of reference solution(μg/ml); Ax is the peak area of tanshinone IIA in test solution; As is the peak area of tanshinone IIA in reference solution; W is weight of the powder (g); D is the conversion factor of the dilute volume and concentration units; is the average weight per tablet(g).