Most chromatographic fillers use silica gel, and are mainly micron-sized spheres. Microsphere silica gel has uniform particle size, stable chemical properties, high mechanical strength, and rich hydroxyl groups on the surface. Silica gel for chromatography is an essential functional material for separation and purification of pharmaceuticals, biotechnology, specialty chemicals, and other chemical industries.By combining certain specific functional groups or ligands with the hydroxyl groups on the surface of silica gel through appropriate chemical methods, the applicable range of the surface to pH values can be changed to expand its application areas.