Preparation of "click" binaphthyl stationary phase and its application for separation of anthraquinones from Rheum palmatum L.

An organosilane containing binaphthyl functional group was synthesized by clicking 2,2'-bis(prop-2-ynyloxy)-1,1'-binaphthyl with 3-azidopropyltriethoxysilane (AzPTES). The "click" binaphthyl stationary phase was then synthesized by covalently bonding the organosilane onto silica beads. In this synthetic method, the residue of copper iodide (CuI) catalyst can be controlled at a very low level. Polycyclic aromatic hydrocarbons (PAHs) were well retained on the "click" binaphthyl column, and showed different retention factors (k) and separation ratio (α) values from those on octadecylsilyl (ODS) column due to the π-π interaction between the analytes and the stationary phase. The anthraquinone compounds in Rheum palmatum L. were selectively separated and enriched into a fraction by the "click" binaphthyl column. By using this way, the complexity of the sample was largely reduced. Twelve of anthraquinones were recognized by UPLC-ESI-MS/MS. This stationary phase will be very useful for separating and enriching similar compounds with planar aromatic structures from complex traditional Chinese medicine (TCM) samples.