Efficient separation of tanshinones by polyvinylpyrrolidone‐stabilized graphene‐modified micellar electrokinetic chromatography

In this work, a PVP-stabilized graphene was used in MEKC for the separation of tanshinones. Seven structurally similar tanshinones were studied, that is, tanshinone IIB, dihydrotanshinone I, tanshinone I, cryptotanshinone, 1,2-dihydrotanshinone I, miltirone, and tanshinone IIA. To achieve optimal conditions, graphene concentration, sample solvent composition, SDS concentration, 2-propanolconcentration, and buffer pH were investigated. At a separation voltage of 30 kV and a 41.5 cm effective length fused-silica capillary, good resolution within 12 min was performed using 10 mM borate buffer (pH 9.3) containing 30 mM SDS, 10% v/v 2-propanol and 6 μg/mL graphene. The method was validated in terms of linearity (r(2) > 0.9970), intra- and inter-day precision were less than 3.56 and 4.83%, respectively. The proposed method was then successfully applied to Danshentong capsule, an herbal preparation from Salvia miltiorrhiza. Our results indicated the high separation efficiency of PVP-stabilized graphene provided new opportunities for the analysis of complex samples.