Simultaneous Determination of Protoberberine Alkaloids Derived from Coptidis Rhizoma and Phellodendri Cortex in Pharmaceuticals by On-line Solid-Phase Extraction (SPE)-High Performance Liquid Chromatography with Ultraviolet Detection (HPLC-UV)

An automated on-line solid-phase extraction (SPE) high-performance liquid chromatography (HPLC) method was developed for the determination of six protoberberine alkaloids in compound Chinese medicines containing Coptidis Rhizoma and Phellodendri Cortex. The sample solution extracted by acidic-methanol was loaded into the constructed system directly to perform enrichment and the purification of the analytes was performed automatically. A cation-exchanged sorbent based on turbulent chromatography was employed for on-line SPE to remove macro and neutral matrix interferences from samples. The target alkaloids were retained on the SPE column and eluted onto the trapping C18 column by a mobile phase of methanol/500 mM ammonium acetate (85:15) at a flow rate of 0.3 mL/min. Ion pair reverse phase high-performance liquid chromatography was employed to complete the determination of six analytes. The results showed the linear correlation coefficients for all analytes were above 0.999. The peak area of relative standard deviation in reproducibility measurements were from 0.55% to 2.39%. Recovery measurements spiked at two levels were from 92.71% to 104.28%. The reported method was suitable for the determination of six active alkaloids in multicomponent Chinese medicines containing Coptidis rhizoma and Phellodendri cortex.