HPLC Determination of 5 Alkaloids in Sophora Flavescens Ait with Microwave Assisted Extraction

Sample of the crushed drug with sizes between 0.18-0.25 mm was placed in a closed extraction vessel and treated by microwave assisted extraction for 5 min with H2O at 110 ℃ under a pressure of 15 MPa, with microwave power of 780 W (PMAE). After centrifugation, the supernatant was collected as the extract. After purification by treatment with absolute alcohol, the analyte in methyl alcohol was used for analysis. Aliquots were taken for qualitative analysis by LC-MS, and for quantitative analysis by HPLC separately. Five alkaloids (i.e., oxymatrine, N-oxysophocarpine, sophoridine, matrine and sophocarpine) were identified by LC-MS. The method of PMAE, as compared with 3 other extraction methods, was proved to be more efficient by having high rate of extraction and requiring less time for extraction. In HPLC analysis, the 5 alkaloids were effectively separated by gradient elution with mobile phase of mixtures of methanol, acetonitrile and 0.1% ammonia solution (pH 10.3) of different ratios on C18 column. Linear relationships between peak area and concentration of the 5 alkaloids were used as basis for quantification. Results of recovery found were in the range of 93.9%-101.0% with RSD′s (n=5) in the range of 0.53%-2.6%.