TY - CONF A1 - Koch, Matthias A1 - Schwake-Anduschus, C. T1 - Distribution of Fusarium mycotoxins and their masked forms in wheat mill fractions T2 - 36. Mycotoxin Workshop CY - Göttingen DA - 2014-06-16 PY - 2014 AN - OPUS4-32437 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koch, Matthias A1 - Bremser, Wolfram A1 - Köppen, Robert A1 - Siegel, David A1 - Töpfer, Antje A1 - Nehls, Irene T1 - Development of two certified reference materials for acrylamide determination in foods N2 - Certified reference materials (CRMs) are a versatile tool for quality assurance in the chemical laboratory. In the case of acrylamide analysis, the availability of appropriate materials was rather limited. This lack of acrylamide matrix CRMs has now been overcome by the development of two European reference materials (ERM) for the determination of acrylamide in food (crispbread, ERM-BD272, and rusk, ERM-BD274). This article describes the preparation of the materials, provides the results of the homogeneity and stability studies, and presents and discusses the outcome of the certification studies. Expert laboratories from different European countries took part in the certification studies using various analytical methods. The acrylamide mass fractions were certified to 980 µg kg-1 for crispbread and 74 µg kg-1 for rusk. KW - Certified reference materials KW - ERM KW - Acrylamide KW - Crispbread KW - Rusk KW - Quality assurance KW - Homogeneity KW - Stability PY - 2009 DO - https://doi.org/10.1021/jf901329t SN - 0021-8561 SN - 1520-5118 VL - 57 IS - 18 SP - 8202 EP - 8207 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-19888 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 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 - CONF A1 - Koch, Matthias A1 - Sebald, M. T1 - Novel Approach towards the Synthesis of Deuterium-labelled Alternariol- and Alternariol monomethylether-Standards for the HPLC-MS/MS-Analysis in Food & Feed N2 - Alternariol (AOH) and Alternariol monomethylether (AME) are two secondary metabolites of Alternaria fungi which can be found in various foodstuffs like tomatoes, nuts and grains. Due to their toxicity and potential mutagenic activity, the need for the development of high-throughput methods for the supervision of AOH- and AME-levels is of increasing interest. As the availability of both native and labelled AOH and AME analytical standards is very limited we herein wish to present a novel concise approach towards their synthesis employing a ruthenium-catalyzed ortho-arylation4 as the key step. T2 - 15th International Symposium on Biological and Environmental Reference Materials (BERM) CY - Berlin, Germany DA - 23.09.2018 KW - Mycotoxins KW - Stable-Isotope-Dilution-Analysis PY - 2018 AN - OPUS4-46489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keller, Julia A1 - Hantschke, Luisa A1 - Haase, H. A1 - Koch, Matthias T1 - Synthesis and Structural Identification of a Biaryl Ether-Linked Zearalenone Dimer N2 - A new dimer of the food-relevant mycotoxin zearalenone was isolated after electrochemical and chemical oxidation. The structure was determined as a 16-O-15'-biaryl ether-linked dimer based on spectroscopic analyses (1H- and 13C-NMR, COSY, HMBC, and HSQCAD) and high-Resolution mass spectrometry analysis (Q-TOF). KW - Mycotoxin KW - Dimerization KW - HRMS KW - NMR PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464940 DO - https://doi.org/10.3390/molecules23102624 SN - 1420-3049 VL - 23 IS - 10 SP - 2624 EP - 2628 PB - MDPI CY - Basel AN - OPUS4-46494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koch, Matthias T1 - Metrological infrastructure for emerging food contaminants by innovative analytical tools T2 - EURAMET EMPIR "Health" Conference CY - Rotterdam, The Netherlands DA - 2015-11-22 PY - 2015 AN - OPUS4-34980 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maul, Ronald A1 - Warth, B. A1 - Schebb, N.H. A1 - Krska, R. A1 - Koch, Matthias A1 - Sulyok, M. T1 - In vitro glucuronidation kinetics of deoxynivalenol by human and animal microsomes and recombinant human UGT enzymes N2 - The mycotoxin deoxynivalenol (DON), formed by Fusarium species, is one of the most abundant mycotoxins contaminating food and feed worldwide. Upon ingestion, the majority of the toxin is excreted by humans and animal species as glucuronide conjugate. First in vitro data indicated that DON phase II metabolism is strongly species dependent. However, kinetic data on the in vitro metabolism as well as investigations on the specific enzymes responsible for DON glucuronidation in human are lacking. In the present study, the DON metabolism was investigated using human microsomal fractions and uridine-diphosphoglucuronyltransferases (UGTs) as well as liver microsomes from five animal species. Only two of the twelve tested human recombinant UGTs led to the formation of DON glucuronides with a different regiospecificity. UGT2B4 predominantly catalyzed the formation of DON-15-O-glucuronide (DON-15GlcA), while for UGT2B7 the DON-3-O-glucuronide (DON-3GlcA) metabolite prevailed. For human UGTs, liver, and intestinal microsomes, the glucuronidation activities were low. The estimated apparent intrinsic clearance (Clapp,int) for all human UGT as well as tissue homogenates was <1 mL/min mg protein. For the animal liver microsomes, moderate Clapp,int between 1.5 and 10 mL/min mg protein were calculated for carp, trout, and porcine liver. An elevated glucuronidation activity was detected for rat and bovine liver microsomes leading to Clapp,int between 20 and 80 mL/min mg protein. The obtained in vitro data points out that none of the animal models is suitable for estimating the human DON metabolism with respect to the metabolite pattern and formation rate. KW - Deoxynivalenol KW - Glucuronidation KW - Uridine-diphosphoglucuronyltransferases (UGT) KW - Human recombinant UGT KW - Trichothecene KW - Phase II metabolism PY - 2015 DO - https://doi.org/10.1007/s00204-014-1286-7 SN - 0340-5761 SN - 1432-0738 VL - 89 IS - 6 SP - 949 EP - 960 PB - Springer CY - Berlin ; Heidelberg [u.a.] AN - OPUS4-33204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koch, Matthias A1 - Köppen, Robert A1 - Siegel, David A1 - Witt, Angelika A1 - Nehls, Irene T1 - Determination of total sulfite in wine by ion chromatography after in-sample oxidation N2 - Sulfur dioxide (SO2) or sulfites are the most common preservatives used in winemaking. The level of total SO2 is subject to regulation. Currently, the regulatory determination of total SO2 (including sulfites) is done by the optimized Monier–Williams (OMW) method, which includes time-consuming distillation and titration steps. This paper describes the development and application of an alternative, rapid, straightforward, and reliable method for the determination of total sulfite in wine. In this method, a simple oxidation step using alkaline hydrogen peroxide (H2O2) solution is followed by ion chromatographic (IC) analysis of sulfate coupled with conductometric detection. Thirteen wines were analyzed in order to compare the in-sample oxidation method with the OMW-procedure. A t-test revealed satisfying compliance regarding sample preparation, i.e., alkaline H2O2 treatment and acidic distillation (OMW method). Comparable results were also obtained between IC analysis and acid/base titration. Our results indicate that the novel method (limit of quantification: 4 mg SO2 L-1) is well suited for the cost-efficient monitoring of regulatory limits. KW - Sulfur dioxide KW - Wine analysis KW - Hydrogen peroxide oxidation KW - IC KW - Optimized Monier-Williams method PY - 2010 DO - https://doi.org/10.1021/jf102086x SN - 0021-8561 SN - 1520-5118 VL - 58 IS - 17 SP - 9463 EP - 9467 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-21912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drzymala, Sarah A1 - Herrmann, Antje A1 - Maul, Ronald A1 - Pfeifer, Dietmar A1 - Garbe, L.-A. A1 - Koch, Matthias T1 - In vitro phase I metabolism of cis-zearalenone N2 - The present study investigates the in vitro phase I metabolism of cis-zearalenone (cis-ZEN) in rat liver microsomes and human liver microsomes. cis-ZEN is an often ignored isomer of the trans-configured Fusarium mycotoxin zearalenone (trans-ZEN). Upon the influence of (UV-) light, trans-ZEN isomerizes to cis-ZEN. Therefore, cis-ZEN is also present in food and feed. The aim of our study was to evaluate the in vitro phase I metabolism of cis-ZEN in comparison to that of trans-ZEN. As a result, an extensive metabolization of cis-ZEN is observed for rat and human liver microsomes as analyzed by HPLC-MS/MS and high-resolution MS. Kinetic investigations based on the substrate depletion approach showed no significant difference in rate constants and half-lives for cis- and trans-ZEN in rat microsomes. In contrast, cis-ZEN was depleted about 1.4-fold faster than trans-ZEN in human microsomes. The metabolite pattern of cis-ZEN revealed a total of 10 phase I metabolites. Its reduction products, α- and β-cis-zearalenol (α- and β-cis-ZEL), were found as metabolites in both species, with α-cis-ZEL being a major metabolite in rat liver microsomes. Both compounds were identified by co-chromatography with synthesized authentic standards. A further major metabolite in rat microsomes was monohydroxylated cis-ZEN. In human microsomes, monohydroxylated cis-ZEN is the single dominant peak of the metabolite profile. Our study discloses three metabolic pathways for cis-ZEN: reduction of the keto-group, monohydroxylation, and a combination of both. Because these routes have been reported for trans-ZEN, we conclude that the phase I metabolism of cis-ZEN is essentially similar to that of its trans isomer. As trans-ZEN is prone to metabolic activation, leading to the formation of more estrogenic metabolites, the novel metabolites of cis-ZEN reported in this study, in particular α-cis-ZEL, might also show higher estrogenicity. KW - Cis-ZEN KW - Phase I metabolism KW - LC-MS/MS KW - HRMS KW - Depletion kinetics PY - 2014 DO - https://doi.org/10.1021/tx500312g SN - 0893-228X SN - 1520-5010 VL - 27 IS - 11 SP - 1972 EP - 1978 PB - Soc. CY - Washington, DC, USA AN - OPUS4-32071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schloß, Svenja A1 - Koch, Matthias A1 - Rohn, S. A1 - Maul, R. T1 - Development of a SIDA-LC-MS/MS method for the determination of phomopsin A in legumes N2 - A novel method for the determination of phomopsin A (1) in lupin flour, pea flour, and bean flour as well as whole lupin plants was established based on stable isotope dilution assay (SIDA) LC-MS/MS using 15N6-1 as an isotopically labeled internal standard. Artificially infected samples were used to develop an optimized extraction procedure and sample pretreatment. The limits of detection were 0.5–1 µg/kg for all matrices. The limits of quantitation were 2–4 µg/kg. The method was used to analyze flour samples generated from selected legume seeds and lupin plant samples that had been inoculated with Diaporthe toxica and two further fungal strains. Finally, growing lupin plants infected with D. toxica were investigated to simulate a naturally in-field mycotoxicosis. Toxin levels of up to 10.1 µg/kg of 1 were found in the pods and 7.2 µg/kg in the stems and leaves. KW - Diaporthe toxica KW - Stable isotope dilution assay KW - Isotopic labeled internal standard KW - Legume contamination PY - 2015 DO - https://doi.org/10.1021/acs.jafc.5b04792 SN - 0021-8561 SN - 1520-5118 VL - 63 IS - 48 SP - 10543 EP - 10549 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-35071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -