Synthesis and characterization of a multimode stationary phase: Congo red derivatized silica in nano-flow HPLC.

A novel Congo red (CR) derivatized silica stationary phase was prepared and packed into a fused silica capillary tube for nano-flow HPLC. A variety of analytes including poly-aromatic hydrocarbons, parabens, acids, sulfonamides, bases, and nucleosides were successfully separated using the CR. In comparison with commercial ODS columns, this new stationary phase has a different separation mechanism (hydrophobically-assisted ion-exchange), which was evident in the separation of benzoic acid derivatives and sulfonamides. The successful application of CR-bonded silica stationary phase in the HILIC and PALC modes demonstrates the effectiveness of this potential chromatographic material in nano flow HPLC.