[Determination of four alkaloids in compound Kushen Injection by high performance liquid chromatography with ionic liquid as mobile phase additive].

In order to improve the resolution and peak shape, 1-butyl-3-methylimidazolium tetrafluoroborate ( [ BMIM] BF4 ) was used as mobile phase additive to develop an HPLC method for the determination of four main alkaloids in Compound Kushen Injection. An Agilent TC-C18 column was used with the mobile phase of methanol-0.1% phosphoric acid solution (containing 2. 2 x 10(4) mol/L [BMIM] BF4 ) (5: 95, v/v) , flow rate of 1.0 mL/min, column temperature of 30 degree C, and injection volume of 20 micro L, detected at 205 nm. The calibration curves of matrine, sophoridine, oxymatrine and oxysophocarpine were in good linearity over the ranges of 25.8 -155.0 mg/L, 40.0 -240.0 mg/L, 21.7 - 130.0 mg/L and 37.5 -225.0 mg/L, respectively, with correlation coefficients above 0. 999 0. The mean recoveries (n = 9) were between 96. 2% and 98.9%. Ionic liquid, [BMIM] BF4, can obviously improve the resolution and peak shape. The method is simple, rapid, and reliable, and can be used for the determination of alkaloids in Sophora flavescens Ait in Compound Kushen Injection.