Influence of the TiO2 content on the chromatographic performance and high pH stability of C18 titanized phases

To extend pH stability, protective metal oxide layers, such as titanium oxide, that are more stable in alkaline medium, can be chemically bonded to the chromatographic silica surface prior to reaction with silanes. In the present work, the influence of the titanium oxide content on the chromatographic performance was investigated by synthesizing a C18 phase onto a doubly-titanized silica support and comparing its chromatographic performance with a C18 phase on singly-titanized silica. The Engelhardt and Tanaka test mixtures were used for chromatographic characterizations using short HPLC columns. The column lifetimes of these titanized phases were also compared by performing accelerated aging tests at 50 °C using aggressive phosphate mobile phases at pH 10.