应用响应面法优化了乙醇微波辅助萃取农吉利中牡荆素和异牡荆素的条件,用高效液相色谱法测定提取液中牡荆素和异牡荆素的含量。用单因素试验选取了萃取温度、液料比及萃取时间等3项条件,并在此基础上,用中心组合试验设计,采用三因素三水平数学模型和响应面法分析进行优化,确定了最优提取条件为:① 萃取温度152 ℃;② 液料比为44∶1;③ 萃取时间6.6 min。在此条件下牡荆素和异牡荆素的提取率分别为253.3,236.9 μg·g-1,与理论值相近。样品加标回收率分别在97.0%~104%和96.0%~102%之间。

The conditions for microwave assisted extraction of vitexin and isovitexin in Crotalaria sessiliflora L. with ethanol were optimized by applying the response surface method. Contents of vitexin and isovitexin in the extracts were determined by HPLC. Single factor testings were performed to select the conditions of extraction temperature, volume (mL) to mass (g) ratio of extracting solvent (C2H5OH) to sample and extraction time; and the conditions were optimized further by applying the central composite design principle at the mode of 3-factors and 3-levels, and the response surface analysis. The optimum extraction conditions found finally were as follow: ① extraction temperature of 152 ℃; ② ratio of C2H5OH (mL) to sample (g) of 44∶1; ③ extraction time of 6.6 min. Rate of extraction obtained under the optimum conditions attained to 253.3 μg·g-1 (for vitexin) and 236.9 μg·g-1 (for isovitexin), which were very close to the theoretical values. Values of recovery obtained by standard addition method were in the ranges of 97.0%-104% for vitexin and 96.0%-102% for isovitexin.