BAM Dissertationsreihe
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- 2011 (1)
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- Dissertation (1)
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- Englisch (1)
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Schlagworte
- Zearalenone (1) (entfernen)
71
Mycotoxins are toxic secondary metabolites of ubiquitously occurring moulds. Through the consumption of contaminated foods, they can cause acute or chronic intoxications in humans. Here, it is demonstrated how covalent hydrazine chemistry can be used to improve the performance of instrumental methods for the quantification of trace level food mycotoxins. In the case of the Alternaria mycotoxin tenuazonic acid, pre-column derivatisation with 2,4-dinitrophenylhydrazine resolved chromatographic issues due to the chemical properties of the analyte and allowed for its rapid, sensitive and selective quantification in cereals and beer by high performance liquid chromatography- ion-trap two stage mass spectrometry (HPLC-IT-MS2). Tenuazonic acid could be detected for the first time in beer and buckwheat flour. Although the encountered levels were too low to cause acute intoxications, the frequency of contamination indicated possible health risks due to chronic exposure. In a second scenario, dynamic covalent hydrazine chemistry (DCHC) was exploited for a novel extraction and cleanup method applicable to the Fusarium mycotoxin zearalenone occurring in edible oils. Zearalenone was extracted by hydrazone formation on a hydrazinefunctionalised polymer resin and subsequently released hydrolytically for quantification by HPLC-fluorescence detection (HPLC- FLD). The high selectivity of the approach allowed for the omission of MS detection and immunoaffinity cleanup. The DCHC method was superior to previously published methods in terms of handling efforts, cost, precision and selectivity and is well suited for the monitoring of the current European maximum level for zearalenone in refined maize oil. In the second part of the dissertation, possible degradation routes of Alternaria mycotoxins upon storage and bread baking are discussed. In the frame of a kinetic study, it was shown that tenuazonic acid is degraded by two parallel processes, deacetylation and epimerisation, when stored in aqueous solution (half-life at 25 °C ~ 74 days). The primary degradation product deacetyl tenuazonic acid was less stable than its parent compound and degraded rapidly in beverage matrices. In model baking experiments it was furthermore revealed that alternariol, alternariol monomethyl ether and altenuene are stable under typical baking conditions. A newly identified degradation route, which is based on a sequence of hydrolysis and decarboxylation, caused only minor substance losses (< 1 %). Still, the degradation products could be detected in commercial rusk and crispbread by HPLC-tandem mass spectrometry (HPLC-MS/MS).