Fate, pathways and methods for the determination of selected antibiotics and steroid hormones in the environment
Pharmaceuticals are mainly introduced into the environment via two pathways. The first path is the application of veterinary drugs to animals, as they are excreted, high concentration are found in manure. As this contaminated manure is utilised for fertilising the fields a soil issue arises. The second path is the treatment of infections in the human medicine. When these residues are excreted they are transported through the sewers to sewage treatment plants and are then discharged with the treated wastewater into the aquatic environment. In this thesis the enviromental fate of the antibiotics erythromycin, roxithromycin, clarithromycin, tylosin, oleandomycin, tiamulin, salinomycin, the steroid hormones 17 β-estradiol, estrone, estriol, 16 α-hydroxyestrone and β-estradiol 17-acetate, the hormone-conjugates β-estradiol 3-sulfate and estrone 3-sulfate, the oral contraceptives 17 α-ethinylestradiol and mestranol were studied. To assess the fate of the macrolide antibiotics, ionophores, pleuromutilins, steroid hormones, oral contraceptives and hormone-conjugates, three new analytical methods were developed in respect of the different matrices manure, soil and wastewater. These analytical methods are based on the extraction methods liquid liquid extraction (LLE), solid phase extraction (SPE) and accelerated solvent extraction (ASE) in combination with the clean-up steps SPE, size exclusion chromatography (SEC) and the detection in different ionisation modes of highperformance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Isotopic labelled internal standards were used to account for matrix-effects in the HPLC-MS/MS analysis. As the availability of deuterated macrolide antibiotics standards is poor, a new macrolide internal standard was synthesised. For the determination of veterinary pharmaceuticals the limit of quantifications (LOQ) were determined. They were between 1.4 and 11 ng/g for manure and 0.6 to 30 ng/g in soil, whereas the LOQ in wastewater ranged from 0.6 to 35 ng/L . For the analysis of the steroid hormones and macrolide antibiotics in wastewater compliance within EU decision 657/2002/EC was achieved. The fate of the veterinary used antibiotics was studied with degradation experiments under anaerobic and aerobic conditions in manure and soil. Half-lives for antibiotics in manure ranged from 5 days up to >200 days and half-lives in soil ranged from 5 days up to >120 days. Additionally new metabolites of the antibiotic salinomycin in manure were identified by means of high performance liquid chromatography with electrospray ionisation coupled with high resolution time of flight mass spectrometry (HPLC-ESI-HR-TOF-MS) and different tandem mass spectrometric techniques. The fate of steroid hormones and macrolide antibiotics during wastewater treatment was researched by testing the elimination efficiencies of three different concepts of STPs over four weeks at different weather conditions. While larger STPs eliminated hormones more constantly than smaller STPs, heavy rainfall events led to a collapse of the biological treatment step. By using trickling filter techniques for the treatment of wastewater an elimination of the steroid hormones could not be observed. Also no significant elimination of macrolide antibiotics during wastewater treatment could be detected in all three STPs.
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