Microwave-assisted extraction and ionic liquid-based dispersive liquid–liquid microextraction followed by HPLC for the determination of trace components in a Langdu preparation†
A novel, simple and efficient sample preparation procedure was established for the fast extraction and preconcentration of six trace components, daphnetin, scopoletin, umbelliferone, daphnoretin, isopimpinellin and ebracteolata compound B, in a traditional Chinese drug Langdu preparation using a combination of microwave-assisted extraction (MAE) and ionic liquid-based dispersive liquid–liquid microextraction (IL-based DLLME) coupled with high-performance liquid chromatography (HPLC). Several important parameters affecting extraction performance, such as microwave power, temperature and irradiation time; type and volume of extraction solvent; type and volume of dispersion solvent; centrifugation speed and time; pH of sample solution and salt concentration, were evaluated. Under optimal experimental conditions, the method exhibited a good performance in terms of linearity with correlation coefficients over 0.9993 and limits of detection (LODs) within the range 0.28–0.56 ng mL−1. The present method was applied to determine the above six analytes in a Langdu preparation named the ‘Jieheling’ tablet and the extraction recoveries obtained were in the range of 80.1–92.9%. The results indicated that the proposed method is an accurate, rapid and reliable technique, which gives excellent enrichment factors (EFs) and LODs for the extraction and preconcentration of trace analytes from a complex matrix.