Preparation and application of UPLC silica microsphere stationary phase:A review.

In this review, microspheres for ultra-performance liquid chromatography (UPLC) were reviewed in accordance with the literature in recent years. As people's demands for chromatography are becoming more and more sophisticated, the preparation and application of UPLC stationary phases have become the focus of researchers in this field. This new analytical separation science not only maintains the practicality and principle of high-performance liquid chromatography (HPLC), but also improves the step function of chromatographic performance. The review presents the morphology of four types of sub-2 µm silica microspheres that have been used in UPLC, including non-porous silica microspheres (NPSMs), mesoporous silica microspheres (MPSMs), hollow silica microspheres (HSMs) and core-shell silica microspheres (CSSMs). The preparation, pore control and modification methods of different microspheres are introduced in the review, and then the applications of UPLC in drug analysis and separation, environmental monitoring, and separation of macromolecular proteins was presented. Finally, a brief overview of the existing challenges in the preparation of sub-2 µm microspheres, which required further research and development, was given.

Preparation and application of urea-based derivatized ß-cyclodextrin chiral stationary phase based on diazotized silica microspheres.

Recently, the design and development of efficient chiral stationary phases is still the core and goal of chiral chromatography. In order to quickly separate chiral drugs, we designed and prepared an environmentally friendly small particle chiral stationary phase: p-methylphenylurea-ß-cyclodextrin chiral stationary phase (SiO2@PMPU-ß-CD). Firstly, p-methylphenylurea-ß-cyclodextrin (PMPU-ß-CD) was connected to the surface of mesoporous silica microspheres by diazoresin (DR) to prepare a SiO2@PMPU-ß-CD. In reverse elution mode, the column temperature was set at 25 °C, the flow rate was 0.2 mL/min, and ACNH2O (v/v = 70:30) was used as the elution condition of the mobile phase. The enantiomers of chlorpheniramine maleate, 2-phenylcyclohexanone, and promethazine were separated within 5 min. In addition, the addition of TEAA buffer to the mobile phase improved the enantiomer resolution of chlorpheniramine maleate from 1.03 to 5.69. The experimental results show that the SiO2@PMPU-ß-CD column can be used for the separation of appellant chiral drugs with good repeatability, and the use of DR instead of silane coupling agent has the advantages of being non-toxic, environmentally protected, and easy to operate, which is of great significance for the development of chiral stationary phase.