engleski

Chromatographic Separation of Veterinary Antibiotics

Increased attention is currently being paid to pharmaceutical substances as a class of emerging environmental contaminants extensively used in human and veterinary medicine. According to European Federation of Animal Health (FEDESA), the total amount of antibiotics used in human therapy and in the veterinary sector to prevent and control of infections or/and for their application as growth promoters was significantly increased in the period 1997-2001. Today, the non-therapeutic use of antibiotics as growth promoters is almost completely abandoned in the EU. On the other hand, the annual application of therapeutic antibiotics has increased in the last few years. Antibiotics used for veterinary purposes can be excreted in the form of the non-metabolised parent compounds or as metabolites and can subsequently enter the environment via manure spread as fertilizer on agricultural land. Due to surface runoff and leaching, soils can act as a source of antibiotic contaminants for the aqueous environment. Excretion of these antibiotics, along with improper waste disposal, has led to considerable concentrations of these compounds. Even the processing of communal wastewater in sewage treatment plants cannot avoid the entry of antibiotics into surface water because of their stability. Possible impacts of antibiotics include toxicity and emergence of antibiotic resistance. SPE/TLC and SPE/HPLC-DAD, methods for concentration, separation and determination of three different classes of antibiotics used in veterinary practice (enrofloxacin, oxytetracycline and trimethoprim) have been developed in this work. These compounds with different physicochemical properties were selected because of their frequent occurrence in wastewater samples. A number of papers describing analytical methodologies for the determination of antibiotics in waters have been published recently. The majority of these studies have used solid-phase extraction (SPE) as a clean-up and pre-concentration step and then chromatographic separation such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) or gas chromatography (GC) with either fluorescence or mass spectrometric (MS) detection. Both fluorescence and MS detection are more sensitive and selective compared with ultraviolet detection, which is advantageous in the case of environmental samples, which generally contain low concentrations of antibiotics. These methods however, have been largely focused on only one, or at most two, classes of compounds. It was therefore necessary to develop an efficient method capable of simultaneously extracting and analyzing of these antibiotics in environmental samples. Owing to our previous experiences in use of chromatography methods in environmental analysis, we have developed methods suitable for monitoring targeted pharmaceutical compounds in the pharmaceutical industry wastewater using solid-phase extraction (SPE) as a preconcentration procedure, followed by thin-layer chromatography like good screening method or followed by high performance liquid chromatography with diode array detector (HPLC/DAD) with lower limits of detection and quantification than TLC.

Thin-layer chromatography; high-performance liquid chromatography; veterinary antibiotics

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