Preparation and characterization of mixed-mode hydrophilic stationary phase based on triple hydrophilic functionalized moieties and its application to traditional Chinese herbal compound

In this paper, the surface modification of spherical silica was sequentially grafted with functional groups including imidazole, amide and sulfonic acid. The novel surface polymerization type stationary phases (SPs) for hydrophilic interaction liquid chromatography (HILIC) were obtained in three procedures. Elemental analysis, Fourier transform infrared spectroscopy, transmission scanning electron microscopy, Brunauer Emmett Teller and Barrett Joyner Halenda were carried out for the characterization of the SPs. The bonding rate of the functionalized group (1-acrylamide propyl sulfonic) was calculated to be 2.02 mu mol/m2. Positive outcomes were attained for the surface grafting of the SPs. The effect of various chromatographic conditions on the retention time of various analytes was investigated on high performance liquid chromatography. The dual retention mechanism of hydrophilic interaction and ion exchange mechanism of the prepared SPs was confirmed. The polymeric HILIC SPs had more abundant functionalized groups on the surface, which provided superior hydrophilic properties, ion exchange and thus higher selectivity. Compared with the C18 column, the resolution of the HILIC column was better. The HILIC SPs were used for the separation of sulfonamides and flavonoid natural components, and had achieved better baseline separations. In addition, the HILIC mode was used for the separation of the extract of the Fructus Ligustri Lucidi, in which the quality markers had satisfactory peak shape and baseline separation. In conclusion, the prepared surface polymeric SPs were competent for the analysis of polar components and applicable to complex samples.