Filtern
Dokumenttyp
- Posterpräsentation (6)
- Zeitschriftenartikel (5)
- Vortrag (2)
Schlagworte
- Transformation products (13) (entfernen)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (2)
Lithium-based batteries (LiBs) have become increasingly important in modern society, as cutting-edge portable energy storage systems and as a crucial component in the energy revolution. However, they still face challenges such as safety concerns, capacity degradation, and the ever-growing demand for higher energy density. To address these issues, researchers have turned their attention to fluorinated organic compounds (FOCs) as part of LiBs electrolytes. These substances, closely related to per- and polyfluorinated alkyl substances (PFAS), have shown great potential in optimizing LiBs. Specifically, their strong fluorine-carbon bond offers enhanced oxidative and chemical resistance. Nevertheless, their environmental impact is a cause for concern. Fluorinated organics can persist in the environment or can lead to the formation of persistent end-products, which accumulate and contribute to global health problems.
To study the fate of fluorinated organic electrolytes in different environmental and application scenarios, a range of simulation methods are employed, including the TOP (Total Oxidizable Precursor) Assay, electrochemistry, photo-induced degradation, and cycling of self-assembled coin cells prepared with FOCs. Transformation products (TP) are identified using gas chromatography and liquid chromatography coupled with high resolution mass spectrometry (GC/LC-HRMS).
The use of per- and polyfluorinated alkyl substances (PFAS), which are very persistent and cannot be completely degraded in the environment, is a well-known problem worldwide. In contrast, fluorinated organic compounds used as electrolytes in lithium-based batteries (LiBs) have been less studied. Despite their increasing use in LiBs due to beneficial properties, such as improving safety, cycling performance, or even enabling high-voltage applications, there is little data on their distribution, transformation, and fate in the environment.
To fill this gap, fluorine-containing electrolyte components are studied in oxidative and reductive transformation processes. The identified transformation products (TP) will be determined in relevant environmental matrices and LiBs.
Lithium-ion battery (LiB) operation remains challenging, particularly in terms of safety, cycling stability, capacity rates and high-voltage applications. Although the electrolytes of LiBs account for 10-15% of the total battery weight, they are still an underestimated part. Data suggest that the composition of electrolytes offers great potential to deal with all these issues. In particular, fluorinated electrolyte solvents or even fluorinated additives offer several advantages due to the strength of the C-F bond, providing chemical and oxidative stability and increased electronegativity, exhibiting flame retardant properties and facilitating anode-mediated degradation, resulting in a LiF-rich and more stable solid electrolyte interphase (SEI), enabling more efficient surface passivation. Therefore, studies suggest that fluorinated equivalents, as well as entirely new compounds, are promising for solving battery-related problems.
But what happens to fluorinated organic compounds (FOCs) during usage? And what are the new potential risks associated with their release into the environment? The environmental and application-specific fate of FOCs is investigated by a selection of different fluorinated electrolytes, the application of various simulation methods, including the TOP (Total Oxidizable Precursor) Assay, electrochemistry, photo-induced degradation, and cycling of FOC-prepared self-assembled coin cells.
Gas chromatography and liquid chromatography coupled with high resolution mass spectrometry (GC/LC-HRMS) are used to identify transformation products (TP).
Identifying the fate of agrochemicals is important to understand their potential risk for living organisms. We report here new photodegradation products (PPs) of the fungicide fluopyram. The PPs were produced by irradiating a fluopyram standard in 0.1% acetonitrile aqueous media by a 150-W medium pressure Hg-lamp that emits wavelengths between 200–280 nm. The structural elucidation of PPs was achieved by combining the retention time, isotopic pattern, targeted fragmentation, and accurate mass measurements using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high resolution-MS (HRMS). In addition to previously known PPs, seven new PPs of fluopyram were identified in this work: mainly dihydroxyl and hydroxylimide fluopyram as well as mono, di, and trihydroxyl lactam. Additionally, two PPs were found to be formed by rearrangement after the loss of H2C=CH2. Hence, the results of the work contribute to extending the current knowledge regarding the photoinduced fate of agrochemicals, and fluopyram in particular.
Within a class of agrochemical residues, pesticides are significant concern due to their various adverse effects on people, animals and the environmental systems. Once they entered to food or to the environment, the parent compound is transformed to metabolites which have different toxicity profiles. Activities like food cooking and waste water treatment (WWT) may lead to produce more toxic metabolites than the parent substances.
Online coupling of electrochemistry with liquid chromatography mass spectrometry (EC-HPLC-MS) is one of the most promising and powerful techniques for metabolite studies which exploited widely for pharmaceuticals so far [1]. However, data on the application of EC-HPLC-MS to simulate environmental transformation products, the fate of contaminants and their metabolic pathways are rare. The oxidation of analyte of interest on the EC, separate the metabolites on HPLC and identifying them by MS gives enormous advantages to identify the contaminants transformation products [2]. Thus, applying this technique (EC-MS, EC-HPLC-MS, and HPLC-EC-MS) for transformation products of pesticide residues is urgently needed.
The main interest of this study will be investigating the electrochemical oxidative degradation products, simulating to in-vitro metabolites and transformation processes of selected pesticides in food and environmental samples. The parent pesticides’, like carbamates and abamectin, oxidation by EC, product metabolites identification and their fates will be discussed using electrochemistry coupled to HPLC-MS techniques.
Nowadays, electrochemistry coupled online to mass spectrometry (EC-MS) or to liquid chromatography-mass spectrometry (EC-LC-MS) is a technique of interest to investigate metabolic transformation of xenobiotics in living organisms. It enables the production of redox products in an electrochemical cell, the separation by an analytical column and the detection by mass spectrometry online. Furthermore, EC-LC-MS enables to determine short lived transformation products (TPs) and their bioconjugates in a fully automated way. Although the EC-MS selectivity is incomparable to enzymatic reactions, it is advantageous by reducing analysis time and matrix complexity compared to cytochrome based metabolism. However, in the development of EC-MS, most efforts are devoted for prediction of drug metabolism in the human body and there is very limited work on agrochemicals in general.
The main objective of this work was to develop an online EC-LC-MS method that could predict the metabolism of fluopyram (fungicide) and chlorpyrifos (insecticide). Oxidation products were produced by using a boron doped diamond electrode and characterized by either online LC-MS or offline LC-MS/MS. After incubation with rat and human liver microsomes, different targeted and suspected metabolites were identified by LC-MS/MS and high resolution-mass spectrometry (HR-MS) and compared with the EC based methods. Additionally, conjugation reactions with a variety of biomolecules such as glucoside and glutathione were investigated by trapping the oxidized species before entering to mass spectrometry.
In summary, phase-I metabolism by N-dealkylation, O-dealkylation, P-oxidation, hydroxylation and dearylation and phase-II metabolism by conjugation with glutathione mechanisms were successfully mimicked by EC-LC-MS. Fluopyram is primarily metabolized to 7- and 8-mono- hydroxyl, 7,8-di-hydroxyl and 2-trifluoromethyl benzamide, and chlorpyrifos is metabolized to chlorpyrifos oxon, trichloropyridinol, diethylthiophosphate and diethylphosphate.
In this work, a study of electrochemical conversion was performed to elucidate different degradation pathways of the heterocyclic brominated flame retardants 1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) and 2,4,6-Tris-(2,4,6-tribromo-phenoxy)-1,3,5-triazine (TTBP-TAZ). EC/MS was used to simulate the (bio)-transformation processes and to identify possible transformation products (TPs) which have never been reported before. For TDBP-TAZTO, six new TPs were observed after the electrochemical oxidation (applied potential of 0 to 1,800 mV vs. Pd/H2). In case of TTBP-TAZ, seven debromination products were generated with an applied potential of 0 to 2,200 mV vs. Pd/H2. The main degradation pathways confirmed by high resolution mass spectrometry for both compounds were hydroxylation, debromination as well as dehydrobromination.
Moxidectin (MOX) is a widely used anthelmintic drug for the treatment of internal and external parasites in food-producing and companion animals. Transformation products (TPs) of MOX, formed through metabolic degradation or acid hydrolysis, May pose a potential environmental risk, but only few were identified so far. In this study, we therefore systematically characterized electro- and photochemically generatedMOX TPs using high-resolution mass spectrometry (HRMS). Oxidative electrochemical (EC) TPs were generated in an electrochemical reactor and photochemical (PC) TPs by irradiation with UV-C light. Subsequent HRMS measurements were performed to identify accuratemasses and deduce occurring modification reactions of derived TPs in a suspected target analysis. In total, 26 EC TPs and 59 PC TPs were found. The main modification reactions were hydroxylation, (de-)hydration, and derivative formation with methanol for EC experiments and isomeric changes, (de-)hydration, and changes at the methoxime moiety for PC experiments. In addition, several combinations of different modification reactions were identified.
For 17 TPs, we could predict chemical structures through interpretation of acquired MS/MS data. Most modifications could be linked to two specific regions of MOX. Some previously described metabolic reactions like hydroxylation or O-demethylation were confirmed in our EC and PC experiments as reaction type, but the corresponding TPs were not identical to known metabolites or degradation products. The obtained knowledge regarding novel TPs and reactions will aid to elucidate the degradation pathway of MOX which is currently unknown.
The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for animal health, food, and environmental matters. The active agent Monensin (MON) belongs to the ionophore antibiotics and is widely used as a veterinary drug against coccidiosis in broiler farming. However, no electrochemically (EC) generated TPs of MON have been described so far. In this study, the online coupling of EC and mass spectrometry (MS) was used for the generation of oxidative TPs. EC-conditions were optimized with respect to working electrode material, solvent, modifier, and potential polarity. 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. The obtained EC-results were compared to TPs observed in metabolism tests with microsomes and hydrolysis experiments of MON.
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.
Two and three further TPs were found as products in microsomal tests and following hydrolysis, respectively. We found decarboxylation, O-demethylation and acid-catalyzed ring-opening reactions to be the major mechanisms of MON transformation.
Analysis of electrochemical and liver microsomal transformation products of lasalocid by LC/HRMS
(2022)
Rationale: Lasalocid (LAS), an ionophore, is used in cattle and poultry farming as feed additive for its antibiotic and growth-promoting properties. Literature on transformation products (TP) resulting from LAS degradation is limited. So far, only hydroxylation is found to occur as the metabolic reaction during the LAS degradation. To investigate potential TPs of LAS, we used electrochemistry (EC) and liver microsome (LM) assays to synthesize TPs, which were identified using liquid chromatography high-resolution mass spectrometry (LC/HRMS).
Methods: Electrochemically produced TPs were analyzed online by direct coupling of the electrochemical cell to the electrospray ionization (ESI) source of a Sciex Triple-TOF high resolution mass spectrometer. Then, EC-treated LAS solution was collected and analyzed offline using LC/HRMS to confirm stable TPs and improve their annotation with a chemical structure due to informative MS/MS spectra. In a complementary approach, TPs formed by rat and human microsomal incubation were investigated using LC/HRMS. The resulting data were used to investigate LAS modification reactions and elucidate the chemical structure of obtained TPs.
Results: The online measurements identified a broad variety of TPs, resulting from modification reactions like (de-)hydrogenation, hydration, methylation, oxidation as well as adduct formation with methanol. We consistently observed different ion complexations of LAS and LAS-TPs (Na+; 2Na+ K+; NaNH4 +; KNH4 +). Two stable methylated EC-TPs were found, structurally annotated, and assigned to a likely modification reaction. Using LM incubation, seven TPs were formed, mostly by oxidation/hydroxylation. After the identification of LM-TPs as Na+-complexes, we identified LM-TPs as K+-complexes.
Conclusion: We identified and characterized TPs of LAS using EC- and LM-based methods. Moreover, we found different ion complexes of LAS-based TPs. This knowledge, especially the different ion complexes, may help elucidate the metabolic and environmental degradation pathways of LAS.