Investigation of the Retention Mechanism of Cephalosporins by Zwitterionic Hydrophilic Interaction Liquid Chromatography

The importance of cephalosporin antibiotics in medicine requires the development of high performance separation methods for their analysis. In this paper cefazolin, cefuroxime, cefoxitin, cefaclor and ceftriaxone were used as model compounds to investigate the retention mechanism under zwitterionic HILIC conditions. The analysis was performed using a ZIC®-HILIC analytical column (150.0 × 2.1 mm i.d., particle size 3.5 μm, 200 A) with isocratic elution. The mobile phase was a mixture of acetonitrile and ammonium acetate or formate buffer. To get a better insight into the retention mechanism on ZIC®-HILIC columns the main factors influencing the retention and selectivity of the analytes have been thoroughly investigated. It is shown that the type of the salt and its concentration along with the volume fraction of water in the mobile phase and pH of the aqueous buffer greatly affect the retention of the tested cephalosporins due to their structures and physicochemical properties. The method was applied successfully to the analysis of injection dosage forms containing cefazolin, cefuroxime and cefoxitin.