TY - JOUR A1 - Keller, Julia A1 - Haase, H. A1 - Koch, Matthias T1 - Hydroxylation and dimerization of zearalenone: comparison of chemical, enzymatic and electrochemical oxidation methods JF - World Mycotoxin Journal N2 - Investigations of the metabolic pathway of mycotoxins by microsomal techniques are often laborious, causing an increasing demand for easy and rapid simulation methods. Thus, the non-microsomal oxidation technique of electrochemistry coupled online to mass spectrometry (EC/MS) was applied to simulate phase I biotransformation of the Fusarium mycotoxin zearalenone (ZEA). The obtained transformation products were identified by high resolution mass spectrometry (FT-ICR) and HPLC-MS/MS. Transformation products (TPs) from EC/MS were compared to those of other oxidative methods such as Fenton-like and Ce(IV) reactions and metabolites derived from in vitro assays (human and rat liver microsomes). Electrochemical oxidization of ZEA was achieved by applying a potential between 0 and 2,500 mV vs. Pd/H2 using a flow-through cell with a boron-doped diamond working electrode. Several mono-hydroxylated TPs were generated by EC/MS and Fenton-like reaction, which could also be found in microsomal in vitro assays. EC and Ce(IV) led to the formation of structurally different ZEA dimers and dimeric quinones probably connected over covalent biaryl C-C and C-O-C bonds. Although the dimerization of phenolic compounds is often observed in natural processes, ZEA dimers have not yet been reported. This is the first report on the formation of stable ZEA dimers and their related quinones. The tested non-microsomal methods, in particular EC/MS, could be useful in order to predict the biotransformation products of mycotoxins, even in cases where one to one simulation is not always feasible. KW - Electrochemistry KW - Zearalenone KW - Dimer PY - 2017 DO - https://doi.org/10.3920/WMJ2017.2213 SN - 1875-0710 SN - 1875-0796 VL - 10 IS - 4 SP - 297 EP - 307 PB - Wageningen Academic Publishers AN - OPUS4-43393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keller, Julia A1 - Haase, Hajo A1 - Koch, Matthias T1 - Electrochemical simulation of biotransformation reactions of citrinin and dihydroergocristine compared to UV irradiation and Fenton-like reaction JF - Analytical and Bioanalytical Chemistry N2 - Mycotoxins occur widely in foodstuffs and cause a variety of mold-related health risks to humans and animals. Elucidation of the metabolic fate of mycotoxins and the growing number of newly discovered mycotoxins have enhanced the demand for fast and reliable simulation methods. The viability of electrochemistry coupled with mass spectrometry (EC/ESI-MS), Fenton-like oxidation, and UV irradiation for the simulation of oxidative phase I metabolism of the mycotoxins citrinin (CIT) and dihydroergocristine (DHEC) was investigated. The specific reaction products are compared with metabolites produced by human and rat liver microsomes in vitro. Depending on the applied potential between 0 and 2000 mV vs. Pd/H-2 by using a flow-through cell, CIT and DHEC are oxidized to various products. Besides dehydrogenation and dealkylation reactions, several hydroxylated DHEC and CIT species are produced by EC and Fenton-like reaction, separated and analyzed by LC-MS/MS and ESI-HRMS. Compared to reaction products from performed microsomal incubations, several mono- and dihydroxylated DHEC species were found to be similar to the reaction products of EC, Fenton-like reaction, and UV-induced oxidation. Consequentially, nonmicrosomal efficient and economic simulation techniques can be useful in early-stage metabolic studies, even if one-to-one simulation is not always feasible. KW - Mycotoxins KW - In vitro KW - Electrochemistry KW - Oxidation PY - 2017 DO - https://doi.org/10.1007/s00216-017-0350-6 SN - 1618-2642 VL - 409 IS - 16 SP - 4037 EP - 4045 PB - Springer CY - Heidelberg AN - OPUS4-40492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koch, Matthias A1 - van de Kreeke, Johannes A1 - Riedel, Juliane A1 - Rasenko, Tatjana A1 - Sommerfeld, Thomas A1 - Sauer, Andreas T1 - PT project „PAH in toys rubber“ N2 - Es werden die Arbeiten und aktuellen Ergebnisse zum Proficiency Test (PT)-Projekt "PAH in toys rubber" vorgestellt. Der PT wurde von der BAM organisiert und erfolgte im Rahmen der deutsch-chinesischen Arbeitsgruppe "Produktsicherheit" (BMWi/AQSIQ). Ziel des PT war es, die Messfähigkeiten deutscher und chinesischer Laboratorien hinsichtlich PAK in Spielzeugprodukten zu bewerten. Hintergrund sind neue PAK-Grenzwerte für Verbraucherprodukte und Spielzeug seit 27.12.2015 (EU-Verordnung 1272/2013). Neben der Herstellung und Charakterisierung des "PAK in Gummi" Referenzmaterials werden im Vortrag die Labor-Ergebnisse vorgestellt, die statistische Auswertung präsentiert und eine Bewertung der verwendeten Analysenverfahren vorgenommen. T2 - Fachworkshop zu den Themen Ringversuch und Referenzmaterialien CY - Xiamen, China DA - 19.10.2017 KW - Polyzyklische aromatische Kohlenwasserstoffe (PAK) KW - Ringversuch KW - Spielzeug PY - 2017 AN - OPUS4-43249 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koch, Matthias A1 - Riedel, Juliane A1 - Rasenko, Tatjana A1 - Bremser, Wolfram T1 - Development of certified reference material and analytical method for zearalenone in edible oil N2 - Quality and safety of food products require their reliable analysis. Contaminants, in particular mycotoxins, are key-components for food safety. About 25 % of the world's food crops are contaminated with mycotoxins posing a severe health risk to humans. In order to strengthen food safety and consumer protection the European Commission (EC) set maximum levels for priority mycotoxins in certain foods for human consumption. In 2013, the EC and CEN (European Committee for Standardization) started an initiative to standardize analytical methods for mycotoxins in food which gained increasing relevance, e.g. zearalenone (ZEN). ZEN, an estrogenic mycotoxin produced by several Fusarium species, contaminates cereal crops worldwide. Due to its lipophilic nature ZEN is often found in edible oils (particularly in maize germ oils) derived from contaminated plants. Therefore, an European maximum level of 400 µg/kg is currently in force. To perform reliable food analysis a sustainable metrological infrastructure is of major importance enabling the quantification of priority mycotoxins (here: ZEN). To achieve this goal, an integrated approach is needed targeted at the development of validated analytical methods and certified reference materials (CRM). A highly selective method for ZEN in edible oils will be presented, based on solid phase extraction (SPE) using hydrazine-functionalized particles. This method was developed for manual application using commercial SPE cartridges as well as for automated SPE-HPLC online coupling. While ZEN is covalently coupled to the solid phase by means of a hydrazone bond, undesired matrix components can be removed very efficiently. Finally, ZEN is decoupled from the solid phase, leading to highly purified extracts which are measured by HPLC-FLD. The development of the first European Reference Material (ERM®) for ZEN in maize germ oil (ERM®-BC715) will be presented and discussed. This ERM®-project underpins the urgent need for mycotoxin-CRMs to support food safety and public health. T2 - 40. Generalversammlung ISO/REMCO CY - Berlin, Germany DA - 27.06.2017 KW - Certified reference materials KW - Mycotoxin KW - Food PY - 2017 AN - OPUS4-40902 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 JF - Analytical and Bioanalytical Chemistry (ABC) 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 - JOUR A1 - Schloß, S. A1 - Hackl, T. A1 - Herz, C. A1 - Lamy, E. A1 - Koch, Matthias A1 - Rohn, S. A1 - Maul, R. T1 - Detection of a Toxic Methylated Derivative of Phomopsin A Produced by the Legume-Infesting Fungus Dioporthe toxica JF - Journal of Natural Products N2 - Phomopsin A (PHO-A), produced by the fungus Diaporthe toxica, is a mycotoxin known to be responsible for fatal liver disease of lupin-fed sheep. The füll spectrum of the toxic secondary metabolites produced by D. toxica is still unknown. PHO-A and the naturally occurring derivatives B—E have been subject to several studies to reveal their structures as well as chemical and toxicological properties. In this work, a methylated derivative of PHO-Aisolated firom lupin seeds inoculated %vith D. toxica is described. It was characterized by high-resolution mass and NMR data and shown to be the N-methylated derivative of PHO-A 1 is cytotoxic againstHepG2 cells. KW - Mycotoxins KW - Identification KW - Food PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411167 DO - https://doi.org/10.1021/acs.jnatprod.6b00662 VL - 80 IS - 6 SP - 1930 EP - 1934 PB - ACS Publications AN - OPUS4-41116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -