The degradation of veterinary drugs by hydrolysis is an important transformation pathway. Additionally, environmental processes can be mimicked on a laboratory scale. A commonly used method is the cell-free incubation with human (HLM) or rat liver microsomes (RLM), because most drugs are metabolized in the liver. Methods of different complexity are known to simulate biotransformations in the laboratory. Among others, EC was used in drug metabolism studies showing that cytochrome P450 mediated metabolic reactions in the liver could be simulated.

EC can simulate a broad reaction spectrum of the sample without complex matrices, which enables a simplified identification of TPs. The substances can be oxidized or reduced depending on the potential polarity. The online-coupling enables the detection of stable TPs but also reactive or short-lived species. One promising instrumental simulation method is based on the combination of electrochemistry (EC) and mass spectrometry. Therefore, TP generation is often simulated by different approaches. The identification of novel TPs in environmental or dung samples using non-targeted liquid chromatography/high resolution mass spectrometry (LC/HRMS) is difficult due to the low concentrations of the drug residues. In the environment, degradation processes like photolysis, hydrolysis, or microbial processes take place whereby TPs are formed. Veterinary drugs are used to cure and prevent animal diseases and are found as residues in animal products as well as in environmental matrices, due to incomplete biotransformation processes and the use of dung as crop plant fertilizer. The derived TPs are potentially more harmful or more persistent than their precursors, rendering TPs, of i.e., veterinary drugs, to be relevant residues in foodstuff or environmental matrices. The formation of TPs can be induced by different processes, for example during the biotransformation in living organisms or during environmental degradation. Transformation products (TPs) are structurally diverse intermediates formed during the (bio)-degradation of organic compounds like drugs. We found decarboxylation, O-demethylation and acid-catalyzed ring-opening reactions to be the major mechanisms of MON transformation. Two and three further TPs were found as products in microsomal tests and following hydrolysis, respectively. Five previously undescribed TPs of MON were identified in our EC/MS based study and one TP, which was already known from literature and found by a microsomal assay, could be confirmed. The obtained EC-results were compared to TPs observed in metabolism tests with microsomes and hydrolysis experiments of MON. Subsequent LC/HRMS (liquid chromatography/high resolution mass spectrometry) and MS/MS experiments were performed to identify the structures of derived TPs by a suspected target analysis. EC-conditions were optimized with respect to working electrode material, solvent, modifier, and potential polarity. In this study, the online coupling of EC and mass spectrometry (MS) was used for the generation of oxidative TPs. However, no electrochemically (EC) generated TPs of MON have been described so far.

The active agent Monensin (MON) belongs to the ionophore antibiotics and is widely used as a veterinary drug against coccidiosis in broiler farming. How “un pote” can become “un ami.The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for animal health, food, and environmental matters. The extra mile for advanced learners: The show Bref (= “In short,” 2-min episodes) did a beautiful story on the subject. –> “Pote” is a more informal, less intimate, synonym for “friend.” It can apply to women too, but we would rather use “une copine.” A French person wouldn’t really say that – it would be really intimate, and/or it could even be a euphemism for “lover.”Ģ – As a French person, if I were to introduce a friend, I’d say something like “C’est Martin, on se connaît de la chorale.” (= Here’s Martin, we know each other from the choir club.) or “C’est Martin, un pote de lycée.” (= Here’s Martin, a friend from high school.)

1 – You CAN use “Je te présente Claude, c’est mon ami / amie.” (= Here’s Claude, he/she is my friend.) You would be understood – but a French person would assume there are cultural differences between you.

Min and mon