Determination of alkaloids in Rhizoma coptidis by capillary electrophoresis with acidic potassium permanganate chemiluminescene detection

Abstract

A simple and sensitive method based on capillary electrophoresis (CE) with acidic potassium permanganate chemiluminescence (CL) detection has been developed for the simultaneous determination of three alkaloids (berberine, palmatine and jatrorrhizine) in Rhizoma coptidis. A lab-built temperature-controlled interface was used for the CL detection. Experimental conditions for CE separation and CL detection were investigated in detail to acquire the optimum conditions. The optimized condition for CL detection was 3.0 × 10⁻⁴ M potassium permanganate in 3.0 M sulfuric acid solution injected by a microinjection pump. With 60 mM phosphate buffer saline (pH = 8.0)–50% (v/v) methanol buffer as the running buffer, the three alkaloids were baseline separated within 13 min at a separation voltage of 18 kV. The calibration curves exhibit excellent linearity with the detection limits ranging from 0.81 to 4.11 μg mL⁻¹ for the three alkaloids. This method was applied for the determination of the abovementioned three alkaloids in Rhizoma coptidis with simple extraction procedures, and the assay results were satisfactory.