Abstract:An ultrasound-assisted homogeneous ionic liquid microextraction tandem high performance liquid chromatography (UA- HILME-HPLC) method was developed and applied to the determination of four tanshinones (dihydrotanshinone, tanshinone I, cryptotanshinone, and tanshinone IIA) expressed in Radix Salvia miltiorrhiza. A water-soluble ionic liquid and water were used as the extraction solvent and extraction media, respectively. The target analytes were extracted using the ultrasound technique. The ion-pairing agent was added to this extraction solution, resulting in the formation of a water-insoluble ionic liquid, which was separated by centrifugation. The separated ionic liquid section was subjected to HPLC analysis. The results of this analysis identified the optimal experimental conditions for UA-HILME to be: 140 μL of the [C8MIM][BF4] extraction solvent, 1 mL of 0.6 mol/L NH4PF6 ion-pairing agent, pH of the sample solution at 5.0, an initial extraction temperature of 50 ℃, 5 min ultrasound extraction time, and 200 W ultrasonic power. All target compounds showed a good linear relationship (r > 0.9996) in the linear range. The observed limits of detection and quantification were 0.02~0.04 μg/mL and 0.07~0.13 μg/mL, respectively. The intra-day and inter-day precision (RSD) was lower than 3.23% and 4.57%, respectively. The spiked sample recovery rate ranged from 83.50% to 96.23%. This method combined the processes of extraction, concentration, purification, and separation, does not require any volatile organic solvents, and shows good results despite a short extraction time and small sample size. Therefore, this method could be widely applied to the extraction and analysis of active components in medicinal plants.
