OBJECTIVEWater content in concentrated extract (WCCE), the concentration of ethanol used in precipitation (CEA) and the quantity of ethanol added( QEA) are three important variables in the first ethanol precipitation of Danshen injection. In this work, the relationships between the three variables and total solid removal, Danshensu (DSS)retention and DSS purity were investigated.

METHODExperiments according to central composite design were carried out and mathematical models were developed.

RESULTThe models were accurate and predictive. The relative deviations between prediction results and experimental results were less than 3%. The influences of the three variables were discussed with a response surface method. The decrease of WCCE and the increase of CEA both caused more precipitation and increase the purity of DSS. However, more loss of DSS was observed. The increase of QEA increased total solid removal. DSS retention and DSS purity increased first and then decreased when QEA increased.

CONCLUSIONThis result suggests the addition of ethanol should be optimized according to WCCE and CEA to obtain better supernatant