TY - JOUR A1 - Mekonnen, Tessema Fenta A1 - Panne, Ulrich A1 - Koch, Matthias T1 - Prediction of biotransformation products of the fungicide fluopyram by electrochemistry coupled online to liquid chromatography-mass spectrometry and comparison with in vitro microsomal assays N2 - Biotransformation processes of fluopyram (FLP), a new succinate dehydrogenase inhibitor (SDHI) fungicide, were investigated by electrochemistry (EC) coupled online to liquid chromatography (LC) and electrospray mass spectrometry (ESI-MS). Oxidative phase I metabolite production was achieved using an electrochemical flow-through cell equipped with a boron doped diamond (BDD) electrode. Structural elucidation and prediction of oxidative metabolism pathways were assured by retention time, isotopic patterns, fragmentation, and accurate mass measurements using EC/LC/MS, LC-MS/MS, and/or high resolution mass spectrometry (HRMS). The results obtained by EC were compared with conventional in vitro studies by incubating FLP with rat and human liver microsomes (RLM, HLM). Known phase I metabolites of FLP (benzamide, benzoic acid, 7-hydroxyl, 8-hydroxyl, 7,8-dihydroxyl FLP, lactam FLP, pyridyl acetic acid, and Z/E-olefin FLP) were successfully simulated by EC/LC/MS. New metabolites including an imide, hydroxyl lactam, and 7-hydroxyl pyridyl acetic acid oxidative metabolites were predicted for the first time in our study using EC/LC/MS and liver microsomes. We found oxidation by dechlorination to be one of the major metabolism mechanisms of FLP. Thus, our results revealed that EC/LC/MS-based metabolic elucidation was more advantageous on time and cost of analysis and enabled matrix-free detection with valuable information about the mechanisms and intermediates of metabolism processes. KW - Metabolism KW - EC/LC/MS KW - Electrochemical oxidation KW - Biotransformation KW - SDHI-fungicide PY - 2018 UR - https://link.springer.com/article/10.1007%2Fs00216-018-0933-x#citeas DO - https://doi.org/10.1007/s00216-018-0933-x SN - 1618-2650 SN - 1618-2642 VL - 410 IS - 10 SP - 2607 EP - 2617 PB - Springer CY - Heidelberg AN - OPUS4-44491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mekonnen, Tessema Fenta A1 - Panne, Ulrich A1 - Koch, Matthias T1 - New photodegradation products of the fungicide fluopyram: Structural elucidation and mechanism identification N2 - 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. KW - Photodegradation KW - Transformation products KW - LC-MS/MS KW - HRMS KW - Fungicide PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-466347 DO - https://doi.org/10.3390/molecules23112940 SN - 1420-3049 VL - 23 IS - 11 SP - 2940, 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-46634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Investigating metabolic transformation processes of pesticides N2 - 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. T2 - 44. Deutscher Lebensmittelchemikertag CY - Karlsruhe, Germany DA - 14.09.2015 KW - Pesticides KW - EC-MS KW - Transformation products PY - 2015 AN - OPUS4-34953 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Transformation products of pesticides: simulation and detection N2 - Pesticides including fungicides, herbicides and insecticides are among primary residues detected in food and feed. They are transformed to a variety of products due to metabolic reactions in living organisms, microbial activities, industrial processes and photochemical reactions. To understand metabolic transformation products (TPs), in-vitro and in-vivo methods were used for a long period of time. However, these conventional methods are hampered by the long-time of analysis and by the matrix complexity. Nowadays, online coupling of electrochemistry with mass spectrometry is a technique of interest for fast prediction/ simulation of metabolic TPs and to understand the mechanism of metabolic processes. The main objective of this work was to understand the mechanism of fluopyram (fungicide) and chlorpyrifos (insecticide) metabolism and to identify TPs by electrochemistry coupled to liquid chromatography-mass spectrometry (EC-LC-MS). Additionally, TPs of fluopyram by photochemical reaction have been investigated. Furthermore, the TPs and parent compounds in real food matrices were investigated by LC-MS/MS. Phase-I metabolism via N- and O-dealkylation, P-oxidation and hydroxylation mechanisms were successfully simulated/predicted by EC-LC-MS. Additionally, metabolites produced by human and rat liver microsomes were identified by LC-MS/MS and high resolution mass spectrometry (HR-MS) and simulated with EC oxidation products. It is known that some phase-I metabolites are further conjugated with different biomolecules such as glucoside and glutathione. Phase-II metabolism was simulated by trapping the oxidized products (phase-I) online by biomolecules and allowing them to react in the loop before the electrospray ionization interface of the MS. Standard solution of fluopyram was irradiated with a medium pressure Hg-lamp (150 W) at 12.5 0C for 2 hrs and aliquots were characterized by LC-MS/MS. In conclusion, the EC-LC-MS method enables fast, cost effective and matrix free detection and prediction of metabolic pathways compared to in-vitro assays. Its versatilities to synthesis reference substances and metabolites for off-line characterization (such as NMR and HR-MS) and possibilities of determining fast reactive intermediates make EC-LC-MS more advantageous than in-vitro assays. T2 - XIX EUROANALYSIS:Europe's Analytical Chemistry Meeting CY - Stockholm, Sweden DA - 28.08.2017 KW - Metabolism KW - EC/LC/MS KW - Transformation product KW - Electrochemical oxidation KW - Photooxidation PY - 2017 AN - OPUS4-42580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Simulation of metabolic transformation products of pesticides by EC-LC-MS N2 - Among major food contaminants agrochemicals (including insecticides, fungicides and herbicides) are a threat for food safety in many countries. Once they entered the food chain or the environment, the parent compound can be transformed into different products by manmade and natural processes. The transformation products (TPs) might be more toxic and stable than the parent compound. In addition to this the transformation products might undergo conjugation with different compounds and/or changed to phase II metabolites. Conventional in-vivo or in-vitro methods to study phase I and II metabolism have drawbacks of long-time sample preparation and matrix complexity. Online coupling of an electrochemical cell with liquid chromatography-mass spectrometry (EC–LC–MS) is a promising technique to study metabolites, fate and transformation products of pesticides. The new approach enables to identify metabolic transformation products by oxidizing analyte of interest on the EC, separate the metabolites on HPLC and identifying them by MS. The aim of the present study is to identify/mimic pesticides phase I metabolites using electrochemical cell coupled to liquid chromatography-mass spectrometry (EC-LC-MS). Metabolic transformed products of two model compounds, fluopyram (fungicide) and chlorpyrifos (insecticide) were studied by EC upfront with MS. The results of EC-LC-MS are compared and discussed with those derived from in-vitro assays and the metabolites identified by LC-MS/MS. T2 - ISEAC39- International Conference Series on Environmental & Food Monitoring CY - Hamburg, Germany DA - 19.07.2016 KW - Metabolic transformation KW - Pesticides KW - EC-MS PY - 2016 AN - OPUS4-36953 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Electrochemistry coupled online to mass spectrometry for prediction of metabolic transformation processes of pesticides N2 - 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. T2 - 13th Annual LC-MS/MS Workshop on Environmental and Food Safety CY - Buffalo, NY, USA DA - 11.06.2017 KW - Biotransformation KW - Transformation products KW - EC-LC-MS KW - Photodegradation PY - 2017 AN - OPUS4-40601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Electrochemistry coupled to mass spectrometry for biotransformation and metabolite elucidation of pesticides N2 - Online coupling of electrochemistry with mass spectrometry (EC/MS) is highly promising for prediction and simulation of metabolic processes of xenobiotics in living organisms. Less time and cost of analysis, matrix free detection, and automation make EC/MS-based metabolomics superior over traditional in-vivo and in-vitro methods. Furthermore, EC/MS has a special feature to identify reactive intermediates and reaction mechanisms. The main objective of this work was to simulate biotransformation processes of pesticides by EC/MS and to elucidate the Transformation products (TPs). We have studied the oxidative phase I metabolism processes of selected pesticides by EC/MS or with liquid chromatography (EC/LC/MS) and compared the derived TPs with cytochrome based metabolites. The electrochemical TPs were produced by boron-doped diamond electrode, separated by LC, and detected by single quadrupole ESI-MS online. Structural identification of both electrochemical oxidation and liver microsome metabolites were based on accurate mass measurements by FT-ICR high-resolution mass spectrometry, isotopic pattern, MS/MS fragmentation, and Retention time alignments. Main phase I oxidative metabolites by P-oxidation, N- & O- dealkylation, dechlorination, hydroxylation, and -OH- oxidation have been identified. Many targeted and untargeted metabolites have been identified by EC/(LC)/MS. Additionally, reactive species have been trapped online by biomolecules to study phase II conjugative reactions. Furthermore, we synthesized TP standards by EC/MS and applied them for pesticide's TPs occurrence investigation in foodstuf matrices. T2 - European Mass Spectrometry Conference (EMSC) 2018 CY - Saarbrücken, Germany DA - 11.03.2018 KW - Transformation product KW - EC/LC/MS KW - Pesticide KW - Biotransformation KW - Electrochemical oxidation PY - 2018 AN - OPUS4-44495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mekonnen, Tessema Fenta A1 - Panne, Ulrich A1 - Koch, Matthias T1 - Electrochemistry coupled online to liquid chromatography-mass spectrometry for fast simulation of biotransformation reactions of the insecticide chlorpyrifos N2 - An automated method is presented for fast simulation of (bio)transformation products (TPs) of the organophosphate insecticide chlorpyrifos CPF)based on electrochemistry coupled online to liquid chromatography-mass spectrometry (EC-LC-MS). Oxidative TPs were produced by a boron doped diamond (BDD) electrode, separated by reversed phase HPLC and online detected by electrospray ionization-mass spectrometry (ESI-MS). Furthermore, EC oxidative TPs were investigated by HPLC-tandem mass spectrometry (LC-MS/MS) and FT-ICR high resolution mass spectrometry (HRMS) and compared to in-vitro assay metabolites (rat and human liver microsomes). Main phase I metabolites of CPF: chlorpyrifos oxon (CPF oxon), trichloropyridinol (TCP), diethylthiophosphate (DETP), diethylphosphate (DEP), desethyl chlorpyrifos (De-CPF), and desethyl chlorpyrifos oxon (De-CPF oxon), were successfully identified by the developed EC-LC-MS method. The EC-LC-MS method showed similar metabolites compared to the in-vitro assay with possibilities of determining reactive species. Our results reveal that online EC-(LC)-MS brings an advantage on time of analysis by eliminating sample preparation steps and Matrix complexity compared to conventional in-vivo or in-vitro methods. KW - Organophosphate agrochemicals KW - Electrochemical oxidation KW - Metabolism KW - In vitro KW - EC-LC-MS KW - LC-MS/MS PY - 2017 DO - https://doi.org/10.1007/s00216-017-0277-y SN - 1618-2642 SN - 1618-2650 VL - 409 IS - 13 SP - 3359 EP - 3368 PB - Springer CY - Berlin Heidelberg AN - OPUS4-40179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Metabolic transformation products of pesticides by electrochemical cell coupled to LC-MS (EC-LC-MS) N2 - Metabolic transformation products (TPs) of the insecticide chlorpyrifos (CPF), the new fungicide fluopyram (FLP) and the broad-spectrum herbicide, glyphosate (GLP), were studied by electrochemistry coupled to mass spectrometry (EC-MS) for the first time. Phase I metabolites of the three pesticides from rat liver in-vitro assay experiments were studied by LC-MS/MS and compared to electrochemically oxidized products from EC-MS. Known metabolites from S-oxidation, O-dealkylation and hydroxylation of the insecticide chlorpyrifos have been identified by EC-MS and simulated to in-vitro assays. Chlorpyrifos-oxon (CPF-oxon), diethylthiophosphate (DETP), 3,5,6-trichloropiridinol (TCP), diethylphosphate (DEP) and 2,3,5-trichloropyridine (TCPy) were the main EC oxidative TPs and in-vitro assay metabolites of CPF which was also reported by Choe et al.. Fluopyram was extensively converted to a number of electrochemical products including mono- and dihydroxylated derivatives and yet unidentified TPs. Rat liver microsomal assay experiments showed mainly hydroxylated metabolites of FLP which was also reported by the European Food Safety Agency (EFSA). Aminomethyl phosphonic acid (AMPA) was the main TP of glyphosate detected from both EC-MS analysis and in-vitro assay tests. A number of TPs of CPF, FLP and GLP have been identified by electrochemistry online mass spectrometry and compared to in-vitro assays. Using electrochemistry upfront MS enables fast and matrix free prediction of metabolic pathways, transformation products and/or fate of pesticides. Further studies will focus on structural characterization of detected compounds, phase II metabolites and investigation of real samples. T2 - 9th European Conference on Pesticides and Related Organic Micropollutants in the Environment: 15th Symposium on Chemistry and Fate of Modern Pesticides CY - Santiago de Compostela, Spain DA - 04.10.2016 KW - EC-MS KW - Pesticides KW - Transformation products (TPs) KW - Metabolites PY - 2016 AN - OPUS4-37707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mekonnen, Tessema Fenta T1 - Investigation of chlorpyrifos and its transformation products in food samples N2 - Chlorpyrifos (CPF), an anticholinesterase organophosphate insecticide, is commonly used to control pests in agricultural sectors. In recent years, it is one of the most frequently detected residues in fruits and vegetables. On the other hand, pesticides including chlorpyrifos undergo extensive abiotic (industrial processes, waste treatments and photodegradations) and/or biotic (metabolism and microbial activities) processes which lead to transformation products (TPs) with different toxicity. Furthermore, lack of representative standards and complexity of transformation mechanisms make monitoring of TPs in real samples difficult. The aim of this work was to investigate CPF and its TPs in selected food matrices. Representative standards of TPs were synthesized by electrochemistry coupled online to liquid chromatography-mass spectrometry (EC/LC/MS) that equipped with a follow-through and/or synthesis cell with boron doped diamond working electrode. The TPs were characterized by LC-MS/MS and high resolution mass spectrometry (HRMS) and used for real sample investigations. Different fruit and spice samples (fortified by TPs standards and blank) were extracted by dispersive solid phase extraction (dSPE) and analyzed by LC-MS/MS. Recoveries were obtained ranging between 94 – 101% (with matrix effect 85 – 97%). The method limit of detection (LOD) and quantification (LOQ) for CPF were 1.9 and 5.7 µg/kg, respectively. Among investigated samples CPF was detected in fresh lemon, black pepper and fenugreek seed with a content of 104, 31 and 4 µg/kg, respectively. Coriander and cinnamon samples also contained trace levels of CPF (