An easy, rapid method for the simultaneous determination of isotetrandrine, curine, sinactine, sinomenine and magnoflorine in Sinomenium acutum was developed by a capillary electrophoresis (CE) method with field-amplified sample stacking (FASS). Parameters affecting CE separation and FASS performance were all carefully investigated to obtain the best sensitivity with the highest speed. Under the optimized conditions: UV detection at 214 nm, separation voltage 25 kV, 40 mM sodium citrate–citric acid (pH 3.5) as running buffer, the detection sensitivity was from 4.8 × 10−9 M to 1.0 × 10−8 M. This resulted in 20–100-fold improvement in concentration sensitivity relative to conventional capillary electrophoresis methods. The relative standard deviation (RSD) of the peak area ratios for repeatability (intraday, n = 5) and intermediate precision (interday, n = 5) were lower than 4.1% and 5.4%, respectively. Finally, the developed method was successfully applied to qualitatively and quantitatively analyze five alkaloids in Sinomenium acutum, with the recovery ranging from 75.5 to 102.2%.
