Ionic Liquid-Based Polarity-Adjustable Deep Eutectic Solvent Extraction Followed by High-Performance Liquid Chromatography-Diode-Array Detection for the Determination of Liposoluble Anthraquinones in Salvia miltiorrhiza Bge. Root.

A simple, green, and efficient ultrasound-assisted deep eutectic solvents (DESs) extraction followed by high-performance liquid chromatography-diode array detector was established to detect four liposoluble anthraquinones in Salvia miltiorrhiza Bge. root. In this study, a series of polarity-adjustable DESs were prepared using n-hexanol and tetrabutylammonium chloride, and their structure, density, viscosity, pH, and thermal stability were determined.