Performance evaluation of 2-undecylimidazole/propyl methacrylate bifunctional silica gel for mixed-mode reversed-phase/anion-exchange chromatography

In this work, 2-undecylimidazole (UI) and propyl methacrylate (PMA) dual-functionalized silica gel was prepared and applied as a mixed-mode chromatographic stationary phase. Successful preparation of this stationary phase (SiO2-UI-PMA) was proved through a range of characterization techniques. The chromatographic performance of the obtained SiO2-UI-PMA was investigated for the separation of environmental endocrine disruptors (phthalates, steroid hormones, bisphenols and alkylphenols), sulfonamides and food-borne stimulants in reversed-phase chromatography, as well as for the separation of inorganic anions in anion-exchange chromatography. The effect of column temperature, acetonitrile content, salt concentration and mobile phase pH on retention was studied to explore the separation mechanism, and the results indicated that this stationary phase provided multiple interactions with analytes. Compared with the commercial C18 column, the SiO2-UI-PMA demonstrated more preferable separation ability under the mobile phase conditions with a low content of acetonitrile, thereby acting as a good alternative candidate for the conventional reversed-phase stationary phase in chromatographic analysis. Furthermore, the SiO2-UI-PMA stationary phase exhibited high column efficiency (45 860 plates m−1 for progesterone) even though it was prepared from the non-serviceable silica based chromatographic packing materials.