Reversed phase HPLC is the most powerful and commonly used technique for the separation of pharmaceuticals. The mobile phases are usually a mixture of polar organic solvents and water. Separations can be isocratic or gradient and are based on analyte hydrophobicity – hydrophobic compounds are retained longer than polar compounds. A common issue with reversed phase separations is non-specific interactions between analytes and the column stationary phase. This undesired effect results from ionic interaction with un-reacted silanols or impurities in the silica gel. This non-specific interaction can cause peak tailing or adsorption as shown in Figures 2a and 2b. CTI's AccuSil columns begin with exceptionally pure, highly characterized silica and use a proprietary bonding and end-capping techniques to eliminate free silanols. This results in columns with excellent peak shape and separation efficiency for all compounds including basic, neutral and acidic analytes.

Superior Column Performance – Separation of Basic Compounds

Many pharmaceuticals are basic, organic, nitrogen-containing compounds. During reversed phase chromatography, these nitrogen groups will react with non-reacted silanol groups on silica-based chromatography supports and can lead to chromatographic artifacts such as shifting retention times or the complete retention of a compound of interest. CTI’s reversed phase supports begin with the purest possible silica and are manufactured with a proprietary process that assures complete end-capping. Furthermore, each column is tested to make sure that no non-reacted silanols remains. The result is excellent chromatography as seen in the left panel below.