Many studies are based on the identification and separation of the polluting antibacterial substances. These compounds reach the environment (water, air, soil) in form of metabolites, conjugated and / or unmetabolized forms. The main pollution source is represented by hospitals, as these units supply about 40% of the antibiotics that reach the environment. As their metabolic transformation has a rate of about 50-60%, these compounds are eliminated in the environment in relatively high quantities. Taking into account the extended utilization of the beta-lactams in the human and veterinary therapy, the aim of the authors was to elaborate a method for the separation of four compounds: benzilpenicillin, amoxicillin, oxacillin and ampicillin. In order to achieve a fast separation, we chose capillary electrophoresis. The analysis was performed on the Agilent Capillary Electrophoresis System equipped with an UV-detector. The acquisition, analysis and interpretation of the results was performed by the Chemstation software. The buffer solution containing 25 mM sodium tetraborate and 100 mM sodium dodecyl sulfate permitted the most efficient separation of the four compounds, the migration order being: amoxicillin, ampicillin, benzilpenicillin and oxacillin. In order to study the influence of the work parameters, we modified the intracapillary tension and temperature; the injection time and pressure and the pH of the buffer solution was modified as well.
Keywords: beta-lactam antibiotics, capillary electrophoresis