Fabrication of polyethyleneimine grafted maleopimaric acid glycidyl methacrylate ester stationary phase for mixed-mode liquid chromatography

Due to their advantages of low green toxicity, diverse sources, renewable nature, and excellent biocompatibility, natural products have been extensively utilized in the exploration and development of novel stationary phase materials for liquid chromatography. In this study, we fabricated a rosin-based stationary phase material for mixed-mode chromatography by utilizing maleopimaric acid glycidyl methacrylate ester (MPAG) and polyethyleneimine (PEI) as ligands. Initially, silica was functionalized with MPAG through thiol-ene click reaction, followed by the grafting of PEI via an imidization reaction to produce Sil-MPAG-PEI material. This material exhibited both anion exchange and hydrophilic interaction properties due to the presence of PEI, allowing for the switching of its retention mode from reversed-phase mode to a mixed-mode incorporating reversed-phase, hydrophilic interaction and ion-exchange chromatography (RPLC/HILIC/IEC) under different mobile phase conditions. Consequently, Sil-MPAG-PEI demonstrated the ability to provide various interactions, including hydrophobic, π-π, hydrogen bond, hydrophilic, ion exchange, and electrostatic interactions. These interactions enabled selective separation among compounds with different polarities, such as nucleosides/bases, benzoic acids, flavonoids, alkylbenzenes, phenols, anilines, and polycyclic aromatic hydrocarbons (PAHs). Furthermore, Sil-MPAG-PEI demonstrated excellent chromatographic stability, as evidenced by the low relative standard deviations (RSDs) of the retention time for interday precision and interday precision were 0.042 %-0.275 % (n = 10) and 0.159 %-0.932 % (n = 7). The column was also successfully employed for the quantitative determination of evodiamine and rutaecarpine in an extract solution of Evodiae fructus, achieving concentrations of 9.102 and 3.256 mg/g, respectively. These results demonstrate the potential of Sil-MPAG-PEI in the analysis of complexsamples. Briefly, this study investigated and confirmed the potential application of rosin derivatives in mixed-mode liquid chromatography separations has been investigated and verified. The exceptional separation ability of Sil-MPAG-PEI indicates that it is a promising separation material for chromatographic separation.