TY - JOUR A1 - Drzymala, Sarah A1 - Riedel, Juliane A1 - Köppen, Robert A1 - Garbe, L.-A. A1 - Koch, Matthias T1 - Preparation of 13C-labelled cis-zearalenone and its application as internal standard in stable isotope dilution analysis N2 - Pure U-[13C18]-labelled cis-zearalenone (cis-ZEA) has been prepared and characterised as internal standard (ISTD) for a reliable quantification of cis-ZEA in contaminated food and feed products. The cis-isomer of the naturally trans-configurated Fusarium mycotoxin zearalenone is often neglected. However, isomerisation easily occurs by exposure of ZEA to (UV-)light. Thus, the applicability of the new cis-ZEA ISTD was demonstrated in a long-term isomerisation study comparing naturally trans-ZEA-contaminated edible oil with spiked edible oil. To estimate the benefits of the newly prepared cis-ZEA ISTD, various approaches to quantify cis-ZEA by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) were compared. As a result, a significant bias was revealed if no appropriate cis-ZEA standards are used. Furthermore, the new ISTD was applied to the analysis of 15 edible oils by stable isotope dilution analysis in combination with HPLC-electrospray ionisation-MS/MS. One of the maize germ oils showed the presence of cis-ZEA above LOD (>0.3 µg/kg), whereas two out of 15 maize germ oils were found to be contaminated with trans-ZEA (range 17.0-31.0 µg/kg). KW - ZEA KW - Zearalenone KW - Isomerisation KW - Occurrence KW - Edible oil KW - SIDA KW - HPLC-MS/MS KW - Quantification KW - LC-MS/MS PY - 2014 DO - https://doi.org/10.3920/WMJ2013.1610 SN - 1875-0710 SN - 1875-0796 VL - 7 IS - 1 SP - 45 EP - 52 PB - Wageningen Academic Publishers CY - Wageningen AN - OPUS4-30126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppen, Robert A1 - Riedel, Juliane A1 - Proske, Matthias A1 - Drzymala, Sarah A1 - Rasenko, Tatjana A1 - Durmaz, V. A1 - Weber, M. A1 - Koch, Matthias T1 - Photochemical trans-/cis-isomerization and quantitation of zearalenone in edible oils N2 - The emphasis of the present work was to investigate the photochemical conversion of trans- to cis-zearalenone in edible oils under real-life conditions. For quantitation purposes a cis-zearalenone standard was synthesized and characterized for its identity and purity (≥95%) by 1H NMR, X-ray crystallography, HPLC fluorescence and mass spectrometric detection. In a sample survey of 12 edible oils (9 corn oils, 3 hempseed oils) from local supermarkets all corn oils contained trans-zearalenone (median 194 µg/kg), but no cis-zearalenone was detected. For alteration studies trans-zearalenone contaminated corn oils were exposed to sunlight over 4 and 30 weeks, revealing an obvious shift toward cis-zearalenone up to a cis/trans ratio of 9:1 by storage in colorless glass bottles. Irradiation experiments of trans-zearalenone in different organic solvents confirmed the preferred formation of cis-zearalenone possibly caused by entropic effects rather than by enthalpic entities as investigated by quantum chemical and classical force field simulations. KW - Fusarium mycotoxins KW - Food KW - Analysis KW - Occurrence PY - 2012 DO - https://doi.org/10.1021/jf3037775 SN - 0021-8561 SN - 1520-5118 VL - 60 IS - 47 SP - 11733 EP - 11740 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-27375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -