Ionic liquid surfactant-mediated ultrasonic-assisted extraction coupled to HPLC: application to analysis of tanshinones in Salvia miltiorrhiza bunge.

Ionic liquid surfactants are a class of ionic liquids (ILs), which can form micelles in the aqueous solution. In this paper, we demonstrate a novel extracting system based on the use of IL surfactants in ultrasonic-assisted extraction followed by HPLC analysis. No organic solvents were used in the extraction, making this method environmentally friendly and more attractive than the conventional organic solvent-based extraction methods. As an example, this method was applied to determine tanshinones in Chinese herbal medicine Salvia miltiorrhiza bunge. The effect of the carbon chain length of the IL cation, as well as other influencing factors on ultrasonic-assisted extraction, was investigated in detail. Under the optimized conditions, satisfactory extraction efficiency was achieved with the recoveries ranging from 87.5 to 107.6%, and the RSDs were lower than 6%. This work shows a promising prospect of the IL surfactants in the extraction of active ingredients from herbs.