TY - JOUR A1 - Mekonnen, Tessema Fenta A1 - Panne, Ulrich A1 - Koch, Matthias T1 - Glucosylation and Glutathione Conjugation of Chlorpyrifos and Fluopyram Metabolites Using Electrochemistry/Mass Spectrometry N2 - Xenobiotics and their reactive metabolites are conjugated with native biomolecules such as glutathione and glucoside during phase II metabolism. Toxic metabolites are usually detoxified during this step. On the other hand, these reactive species have a potential health impact by disrupting many enzymatic functions. Thus, it is crucial to understand phase II conjugation reactions of xenobiotics in order to address their fate and possible toxicity mechanisms. Additionally, conventional methods (in vivo and in vitro) have limitation due to matrix complexity and time-consuming. Hence, developing fast and matrix-free alternative method is highly demandable. In this work, oxidative phase I metabolites and reactive species of chlorpyrifos (insecticide) and fluopyram (fungicide) were electrochemically produced by using a boron-doped diamond electrode coupled online to electrospray mass spectrometry (ESI-MS). Reactive species of the substrates were trapped by biomolecules (glutathione and glucoside) and phase II conjugative metabolites were identified using liquid chromatography (LC)-MS/MS, and/or Triple time of flight (TripleTOF)-MS. Glutathione conjugates and glucosylation of chlorpyrifos, trichloropyridinol, oxon, and monohydroxyl fluopyram were identified successfully. Glutathione and glucoside were conjugated with chlorpyrifos, trichloropyridinol, and oxon by losing a neutral HCl. In the case of fluopyram, its monohydroxyl metabolite was actively conjugated with both glutathione and glucoside. In summary, seven bioconjugates of CPF and its metabolites and two bioconjugates of fluopyram metabolites were identified using electrochemistry (EC)/MS for the first time in this work. The work could be used as an alternative approach to identify glutathione and glucosylation conjugation reactions of other organic compounds too. It is important, especially to predict phase II conjugation within a short time and matrix-free environment. KW - Pesticide KW - Bioconjugation KW - Oxidative metabolism KW - EC/MS PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-475932 VL - 24 IS - 5 SP - 898 EP - 910 PB - MDPI AN - OPUS4-47593 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-466347 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 - 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 U6 - 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 - CONF A1 - Mekonnen, Tessema Fenta A1 - Panne, Ulrich A1 - Koch, Matthias 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 - CONF A1 - Mekonnen, Tessema Fenta A1 - Byrne, Liam A1 - Panne, Ulrich A1 - Koch, Matthias 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 (