Capillary coated with graphene oxide as stationary phase for the separation of brucine and strychnine by capillary electrophoresis.

A new capillary electrophoresis (CE) method was developed by using graphene oxide (GO) as a stationary phase for the separation of brucine and strychnine. The separation performance, reproducibility and stability of GO-coated capillary were investigated for the analysis of brucine and strychnine. After optimization of the separation conditions, a phosphate solution (40 mM, pH 7.0) containing 25% (v/v) acetonitrile was selected as the running buffer. Compared with uncoated capillary, higher separation efficiency was achieved by GO-coated capillary as a result of the increasing interactions between the analytes and the stationary phase of capillary. The linear ranges of these two alkaloids were 4.0-100.0 μg mL(-1) with a satisfied correlation coefficients (R > 0.9994), and this novel method provided an efficient separation of brucine and strychnine as well as a good reproducibility and stability. Finally, the developed method was successfully applied for the determination of these two alkaloids in a pharmaceutical formulation of traditional Chinese medicines.