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The antiepileptic drug carbamazepine is one of the most abundant pharmaceuticals in the German aquatic environment. The effect of low carbamazepine concentrations (1–50 µg L-1) is discussed controversially, but ecotoxicological studies revealed reproduction toxicity, decreased enzymatic activity and bioaccumulation in different test organisms. Therefore, as a preventive step, an efficient and cost-effective technique for wastewater treatment plants is needed to stop the entry of pharmaceuticals into the aquatic environment. Cavitation, the formation, growth, and subsequent collapse of gas- or vapor-filled bubbles in fluids, was applied to solve this problem. The technique of Hydrodynamic-Acoustic-Cavitation was used showing high synergistic effect. Under optimized conditions carbamazepine (5 µg L-1) was transformed by pseudo-first order kinetics to an extent of >96% within 15 min (27% by hydrodynamic cavitation, 33% by acoustic cavitation). A synergistic effect of 63% based on the sum of the single methods was calculated. Carbamazepine concentrations were monitored by a sensitive and selective immunoassay and after 60 min no known metabolites were detectable by LC-MS/MS.
The environmental fate of the frequently used broad-spectrum β-lactam antibiotic amoxicillin (AMX) is of high concern regarding the potential evolution of antimicrobial resistance (AMR). Moreover, it is known that AMX is prone to hydrolysis, yielding a variety of hydrolysis products (HPs) with yet unknown effects. Studies to identify those HPs and investigate their formation mechanisms have been reported but a long-term study on their stability in real water samples was missing. In this regard, we investigated the hydrolysis of AMX at two concentration levels in four distinct water types under three different storage conditions over two months. Concentrations of AMX and four relevant HPs were monitored by an LC-MS/MS method revealing pronounced differences in the hydrolysis rate of AMX in tap water and mineral water on the one hand (fast) and surface water on the other(slow). In this context, the occurrence, relative intensities, and stability of certain HPs are more dependent on the water type than on the storage condition. As clarified by ICP-MS, the main difference between the water types was the content of the metals copper and zinc which are supposed to catalyze AMX hydrolysis demonstrating an effective method to degrade AMX at ambient conditions.