Abstract: In this study,the baicalin was extracted from scutellaria root by single-frequency ultrasonic continuous countercurrent extraction(SUCCE),dual-frequency-complex ultrasonic continuous countercurrent extraction(DCUCCE) and dual-fre-quency-alternant ultrasonic continuous countercurrent extraction(DAUCCE).The experimental plans were done according to uniform design for the maximum extraction of baicalin.The data were processed with PLS procedure and the effects of the factors,such as ultrasonic frequency,power and temperature on factor of extraction ability(FEA) of baicalin were confirmed by the standard regression coefficient.The optimum extraction conditions are determined as follow:solid and liquid rate 1:5,ethanol concentration 70%,ultrasonic power 800 W,extraction time 27 min,extraction temperature 50 ℃;and DCUCCE frequency 25+50kHz.Under the above conditions,FEA of 5.3243g/L·min,was obtained,which is well close to the predicted result,18.6% and 17.4% more than that of SUCCE and DAUCCE respectively,492 times and 131 times of that of classic extraction and ultrasonic intermittent extraction,respectively.Therefore,DCUCCE is worthy of using in industry.

Key words: baicalin, multi-frequency ultrasonic, continuous countercurrent extraction, scutellaria root, uniform design