TY - JOUR A1 - Schloß, Svenja A1 - Wedell, Ines A1 - Koch, Matthias A1 - Rohn, S. A1 - Maul, Ronald T1 - Biosynthesis and characterization of 15N6-labeled phomopsin A, a lupin associated mycotoxin produced by Diaporthe toxica N2 - The hepatotoxin phomopsin A (PHO-A), a secondary metabolite mainly produced by the fungus Diaporthe toxica, occurs predominantly on sweet lupins. Along with the growing interest in sweet lupins for food and feed commodities, concerns have been raised about fungal infestations, and consequently, about the determination of PHO-A. High performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) represents the most suitable analytical technique for sensitive and selective detection of mycotoxins including PHO-A. However, isotopic labeled substances are needed as internal standards for a reliable and convenient quantification. As no isotope standard for PHO-A is currently available, a biosynthesis of fully 15N6-labeled PHO-A was established by cultivation of D. toxica on defined media containing Na15NO3 and 15N-labeled yeast extract as the only nitrogen sources. The identity of 15N6-PHO-A was confirmed by high resolution mass spectrometry. The new 15N6-labeled standard will facilitate the method development for PHO-A including a more accurate quantification by LC-MS/MS. KW - Phomopsin A KW - Lupins KW - Diaporthe toxica KW - Stable isotope dilution assay KW - Isotopic labeled internal standard KW - Biosynthesis PY - 2015 U6 - https://doi.org/10.1016/j.foodchem.2014.12.056 SN - 0308-8146 VL - 177 SP - 61 EP - 65 PB - Elsevier CY - Amsterdam [u.a.] ; Jena AN - OPUS4-32464 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 U6 - 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 -