An overview of the chromatographic properties and stability of C18 titanized phases

Phases based on titanized silicas are an alternative in the search for HPLC stationary phases with enhanced pH stability. This technology explores the chemical modification of the bare silica surface by grafting a titanium oxide layer with the objective of retarding the dissolution of the support in alkaline mobile phases, followed by C18 silanization. The present manuscript describes recent work on the development of chemically bonded titanized phases, including phases containing embedded urea groups, and phases prepared both in the absence and in the presence of a monolayer of water preadsorbed onto the bare silica. The advantages and disadvantages of these alternative C18 titanized phases are discussed, taking into account their chromatographic properties accessed by some common test procedures. Column lifetimes, measured by accelerated aging tests using aggressive conditions, such as high-pH phosphate mobile phases and elevated temperature, are also discussed.