Ultrasonic-Assisted Sol–Gel Synthesis of Core–Shell Silica Particles for High-Performance Liquid Chromatography

Core–shell particles (CSPs), also known as superficially porous particles or fused-core particles, consisting of a solid core and a porous shell, have emerged as an advanced technology in high-performance liquid chromatography (HPLC). We report here an ultrasonic-assisted sol–gel method for the fabrication of CSPs with uniform mesoporous silica shell using tetraethoxysilane as the silica source and dodecylamine as a catalyst, template and porogen agent in a methanol–water solution. Instead of stirring, sonication was adopted to guarantee the particles monodispersity and uniformity. The shell thickness between 300 and 700 nm could be obtained by adjusting the sonication time and the volume ratio of methanol–water. Pore sizes from 3.4 to 8.5 nm were tuned by hydrothermal treatment. The C18-bonded 2.7 μm CSPs with a shell thickness of ~ 500 nm showed some advantages over a commercial 1.7 μm BEH column, and successfully applied for the analyses of a Chinese medicine and peptides. The CSPs could be a promising candidate as HPLC packing materials.