Dispersive Liquid-Liquid Microextraction Combined with High-Performance Liquid Chromatography for the Simultaneous Analysis of Matrine Alkaloids in Traditional Chinese Medicine

Dispersive liquid-liquid microextraction (DLLME), coupled with high-performance liquid chromatography (HPLC), was developed and introduced for simultaneous extraction and determination of the trace level matrine alkaloids (oxymatrine, matrine, sophoridine and oxysophocarpine) in Composite Kushen Injection and Sophorae Flavescentis Radix. Several factors affecting performance were investigated and optimized, including type and volume of extraction solvent, type and volume of disperser solvent, sample phase pH, shaking time, centrifugation time and rate, and salt concentration in the sample solution. Under optimized conditions, the enrichment factors of DLLME for four matrine alkaloids ranged from 0.17 to 83.5; the good linearities were obtained for all analytes with the coefficient of determination of between 0.9924 and 0.9989; the limits of detection were between 0.2 and 275 ng mL(-1); the satisfactory recoveries (86.6-104.5%) and the precision (relative standard deviation (RSD) 2.0-12.2%) were also achieved. The average content of sophoridine, oxymatrine, matrine and oxysophocarpine in Composite Kushen Injection and Sophorae Flavescentis Radix are 0.60, 40.3, 0.17, 0.39 mg mL(-1) with the RSD of 5.3-9.0% (n = 3), and 0.13, 26.7, 1.20, 0.40 mg g(-1) with the RSD of 3.5-9.2% (n = 3). The experimental results showed that the method was a simple, sensitive and practical for simultaneous extracting, enriching and quantifying of the different concentrations level matrine alkaloids in TCM.