Simple Preparation Method of Silica Core–Shell Spheres for HPLC in Undergraduate Chemistry

Abstract

High-performance liquid chromatography (HPLC) experiments are an important part of the undergraduate analytical instrumentation laboratory courses and usually use commercial C18 silica-packed reversed-phase columns. In this experiment, a simple method of preparing SiO2 core–shell packed columns was developed to enable students to master the whole process of HPLC experiment from stationary phase preparation and column packing to separation experiments, just as they do for gas chromatography. Nonporous SiO2 particles with a particle size of approximately 2.2 μm were prepared by a three-step dilution reaction using the sol–gel method. The product yield was 92.1%. Monodisperse and spherical SiO2 core–shell particles (SiO2@dSiO2) with a particle size of about 2.4 μm were prepared by a one-step hydrothermal method using the prepared SiO2 spheres as the core. The product yield was 83.3%. The prepared SiO2@dSiO2 particles were derivatized with n-octadecyldimethylchlorosilane and then packed into a stainless steel chromatography column. A high column efficiency of 83,188 theoretical plates per meter was obtained for fluorene in reversed-phase mode for the separation of a mixture of polycyclic aromatic hydrocarbons. The column efficiency obtained with this method is the same as that of a commercial column packed with fully porous particles of the same particle size. The SiO2 core–shell stationary phase preparation method developed in this experiment has the advantages of simple process, high yield, and good repeatability. The experiment can be designed to be completed over a period of 1–3 weeks. Inorganic material synthesis is another important aspect of this experiment.