Simultaneous separation of two indicator constituents in Salvia miltiorrhiza Bge. from compound Chinese medicine using ionic Liquid@Covalent organic framework (IL@COF) discs.

In this study, an ionic liquid-functionalized covalent organic framework (IL@COF) composite was synthesized by immobilizing different ILs onto a COF support, which possesses a hierarchical porous structure with a high specific surface area (1067.8 m²/g). The IL@COF was subsequently fabricated into 13 mm discs using ethyl cellulose as an excipient. After systematic characterizations, they were applied for the simultaneous adsorption of iconic Tanshinone IIA and Salvianolic acid B in Salvia miltiorrhiza from Danshen oral liquid, promoting its component analysis, quality control, and basic research on the chemistry-bioactivity relationship of such a compound preparation. The adsorption process followed the pseudo-second-order kinetic model and Langmuir isotherm model, indicating chemisorption-dominated monolayer adsorption on energetically homogeneous active sites. Moreover, the adsorption of Tanshinone IIA was exothermic and enthalpy-driven, while the adsorption of Salvianolic acid B was driven by both enthalpy and entropy, with a significant desolvation effect. Surface electrostatic potential (ESP) calculations and independent gradient model based on Hirshfeld partition (IGMH) weak interaction analysis revealed that hydrogen bonding, π-π stacking, and van der Waals forces are the primary non-covalent interactions governing the recognition and binding of the target compounds to the IL. In addition, the developed discs and separation method exhibited satisfied recyclability and friendly greenness, respectively.