title: Photochemical trans-/cis-isomerization and quantitation of zearalenone in edible oils.
abstract: 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 (1)H 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.
authors.affiliation: Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Köppen
authors.forename: Juliane
authors.initials: J
authors.lastname: Riedel
authors.forename: Matthias
authors.initials: M
authors.lastname: Proske
authors.forename: Sarah
authors.initials: S
authors.lastname: Drzymala
authors.forename: Tatjana
authors.initials: T
authors.lastname: Rasenko
authors.forename: Vedat
authors.initials: V
authors.lastname: Durmaz
authors.forename: Marcus
authors.initials: M
authors.lastname: Weber
authors.forename: Matthias
authors.initials: M
authors.lastname: Koch
mesh_terms: D002188:Cannabis; D003314:Corn Oil / Q000737:chemistry; D004355:Drug Stability; D007536:Isomerism; D010777:Photochemistry; D010938:Plant Oils / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D013472:Sunlight; D015025:Zearalenone / Q000032:analysis* / Q000737:chemistry*
chemical_list: D010938:Plant Oils; D015025:Zearalenone; D003314:Corn Oil