Potential Use of an Aminopropyl Stationary Phase in Hydrophilic Interaction Capillary Electrochromatography. Application to Tetracycline Antibiotics

We have demonstrated that the aminopropyl stationary phase (APS2) already used for analysis of polar compounds in hydrophilic interaction liquid chromatography can be successfully used in capillary electrochromatography. First, it was shown that the APS2 packing material affords a sustainable electroosmotic flow, the direction and magnitude of which depend on the nature of the electrolyte ions. A triple-layer model is proposed to describe this particular behaviour of the aminopropyl stationary phase. Finally, application to the separation of the tetracycline antibiotics used as test compounds in capillary electrochromatography is described and it is demonstrated that the final separation may be manipulated because of the electromigration and retention properties of the compounds, although migration times cannot be accurately predicted. Revised: 15 March and 6 July 2005