Study on an Hydrophilic Interaction Electrochromatography Method for Separation of Sulfonamide Antibiotics

This study describes the preparation of a hydrophilic monolithic column and its application to sulfonamide antibiotics. The column was prepared by single step in situ polymerization of 2-hydroxyethyl methacrylate (HEMA), ethylene dimethacrylate (EDMA) and methacrylic acid (MAA) in a binary porogenic solvent consisting of toluene and 1-dodecanol, inside a 100 µm-i.d. capillary. The resulting monolith was electrochromatographically characterized as well as SEM. The prepared column showed hydrophilic behaviour using thiourea and toluene as markers. The SEM images showed that the monolithic column composed of spherical particles of approximately 2 µm in diameter. Using this hydrophilic monolith as stationary phase, hydrophilic interaction electrochromatography of sulfonamide antibiotics as a new method was developed. The method was successfully used for the separation of sulfonamide antibiotics. Some parameters including acetonitrile (ACN) content, pH and ionic strength on the separation of the sulfonamides, namely sulfaprydine, sulfadiazine, sulfamethazine, sulfisoxazole and sulfadoxine were also investigated. A typical hydrophilic interaction separation mechanism was revealed at higher organic solvent content (ACN > 60%).