Dispersive liquid-liquid microextraction based on a supramolecular solvent followed by high-performance liquid chromatographic analysis of lignans in Forsythiae Fructus.

A supramolecular solvent-based dispersive liquid-liquid microextraction was proposed for the extraction and determination of lignans in Forsythiae Fructus combined with high-performance liquid chromatography. The supramolecular solvent, consisting of tetrabutylammonium bromide and n-hexanol, was mixed with the sample solution to extract the analytes by a vortex. After accomplishing the extraction, the extraction phase was separated by centrifugation and collected for high-performance liquid chromatography analysis. In this work, the important extraction variables such as the type and amount of extraction solvent, pH and salt amount in the sample phase, and extraction time were optimized. The synthesis of supramolecular solvent was studied and its microstructure was characterized by transmission electron microscopy. Under the optimal conditions, the analytes' enrichment factors were between 6 and 170 for the proposed procedure. Satisfactory linear ranges (r ≥ 0.99), detection limits (0.025-0.4 ng/ml), precisions (< 9.2%), and accuracies (recoveries: 96.5%-104.8%) were obtained. The method has been successfully applied to the preconcentration of lignans in Forsythiae Fructus with simple and rapid operation, low cost, and environmental friendliness.