[Extraction of three tanshinones from the root of Salvia miltiorrhiza Bunge by supercritical carbon dioxide fluid and their analysis with high performance liquid chromatography].

The extraction of three tanshinones from the root of Salvia miltiorrhiza Bunge by supercritical carbon dioxide (SC-CO2) fluid with ethanol as co-solvent was investigated using four-factor and three-level orthogonal design method and the systematic method. The optimized conditions were established as follows: 95% ethanol was selected as a co-solvent, flow rate of co-solvent was 1.0 mL/min, extraction pressure was 20 MPa, extraction temperature was 45 degrees C, separation temperature was 35 degrees C. The sample solution was separated on a Nova-Pak C18 column (3.9 mm i.d. x 300 mm, 5 microns) with CH3OH-H2O (80:20, V/V) as the mobile phase and detected at 280 nm. The correlation coefficients were 0.9994-0.9998 and the relative standard deviations were 2.37%-3.47%. The detection limits were 0.473 mg/L, 0.184 mg/L and 0.452 mg/L for tanshinone-II A, tanshinone-I and cryptotanshinone respectively.