Simultaneous determination of six triterpenic acids in some Chinese medicinal herbs using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with fluorescence detection.

A novel analytical method was developed for simultaneous determination of six triterpenic acids using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) follow by high-performance liquid chromatography (HPLC) with fluorescence detection. Six triterpenic acids (ursolic acid, oleanolic acid, betulinic acid, maslinic acid, betulonic acid and corosolic acid) were extracted by UA-DLLME using chloroform and acetone as the extraction and disperser solvents, respectively. After the extraction and nitrogen flushing, the extracts were rapidly derivatized with 2-(12,13-dihydro-7H-dibenzo[a,g]carbazol-7-yl)ethyl4-methylbenzenesulfonate. The main experimental parameters affecting extraction efficiency and derivatization yield were investigated and optimized by response surface methodology (RSM) combined with Box-Behnken design (BBD). The limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.95-1.36 ng mL(-1) and 3.17-4.55 ng mL(-1), respectively. Under the optimum conditions, the method has been successfully applied for the analysis of triterpenic acids in six different traditional Chinese medicinal herbs.