Using the silica of high pure and high mechanical strength, the Promosil C18 series columns are made with high pure monosilane through Bonna-Agela Technologies' well controlled bonding process. They have high surface bonding coverage and are completely capped. The carbon content is as much as 18%. They are stable at pH range 1.5-9.0 showing good peak shape for acidic and basic compounds. They have excellent tolerance to contamination and long lifetime. They are the best choice of high performance-to-cost value.