Identification and determination of the major triterpenes in Rhizoma Alismatis by HPLC-evaporative light scattering detection and HPLC/electrospray ionization-MS.

A simple and reliable HPLC-evaporative light scattering detection method was established for the determination of seven triterpenes in Rhizoma Alismatis, a commonly used herbal medicine. HPLC coupled with electrospray ionization-MS was applied to identify the triterpenes. The positive ion mode was used in MS detection, and the fragmentation patterns of the analytes were proposed. The quantitative method was validated for linearity, sensitivity, precision, and accuracy. All calibration curves showed good linearity (r2 > 0.9943) within the test ranges. This method showed good reproducibility with intraday and interday variations of less than 3.39 and 5.20%, respectively. The mean recoveries ranged from 96.06 to 103.5%. The proposed method was successfully applied for the quantitative analysis of the triterpenes in samples from four different habitats. The results indicated great variation of the contents of these components among the samples, and the developed assay could be considered as a suitable quality evaluation method for Rhizoma Alismatis.