RESUMEN
<p><b>OBJECTIVE</b>To establish a method for determining isofraxidin concentrations in Sarcandra glabra and Qingrexiaoyanning capsules with high-performance liquid chromatographic-mass spectrometry.</p><p><b>METHODS</b>Isofraxidin was extracted from Sarcandra glabra and Qingrexiaoyanning capsules with acetic ether and chloroform, respectively, and separated by isocratic reversed-phase chromatography. The mass spectrometric system was operated in multiple reaction monitoring mode. A pair of ions: precursor ion m/z 223 with product ion m/z 162 were chosen for the quantification of the analyte.</p><p><b>RESULTS</b>The retention time of isofraxidin was 6.60 min, and the calibration curve was linear over a concentration range from 484 to 9 680 ng/ml. The average recovery was 96.7% and RSD 4.49%, with detection limit of 1 ng/ml.</p><p><b>CONCLUSION</b>The method is rapid, selective and sensitive for determining isofraxidin in Sarcandra glabra and Qingrexiaoyanning capsules.</p>