Search

A liquid chromatography-high-resolution mass spectrometry-based method is reported for the quantification of 20 selected mycotoxins and the simultaneous screening for 200 fungal metabolites in food. For regulated mycotoxins, such as aflatoxins, fumonisins, ochratoxin A, zearalenone and trichothecenes, the evaluation of the method performance characteristics, such as precision, trueness, limit of detection and matrix effects, has been exemplified for the matrix maize. In the case of the limit of detection, an alternative evaluation approach for high-resolution FT-Orbitrap data is proposed. Measurements of the signal-to-noise ratios obtained from 'full-profile mode' data led to detection limits between 8 and 160 ng g−1. Eight naturally contaminated wheat- and maize-based matrix test materials, originating from interlaboratory comparison studies, were used to confirm the trueness of the method for deoxynivalenol, zearalenone, fumonisin B1 and B2, HT-2, and T-2 toxin. In addition to accurate quantification of the most relevant mycotoxins, the full-scan chromatograms were used to investigate the potential of the FT-Orbitrap to screen simultaneously for a large number of fungal metabolites. First, a list of 200 metabolites, potentially being present in food samples, was established. Next, specific detection and identification criteria were defined, which are based on accurate mass, peak intensity and isotopologue ratio. The application of these criteria to the suspected metabolites from the list resulted in the putative identification of 13 fungal metabolites in addition to the target toxins. [ABSTRACT FROM AUTHOR]

Deoxynivalenol-3-β-D-glucoside (D3G), a phase II plant metabolite of the mycotoxin deoxynivalenol (DON), occurs in naturally Fusarium-contaminated cereals. In order to investigate the frequency of occurrence as well as the relative and absolute concentrations of D3G in naturally infected cereals, 23 wheat samples originating from fields in Austria, Germany and Slovakia as well as 54 maize samples from Austrian fields were analysed for DON and D3G by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both analytes were detected in all the 77 field samples. DON was found at levels from 42 to 4130 ng g-1 (977 ± 1000 ng g-1 on average). The D3G concentrations in all cereal samples were in the range 10-1070 ng g-1 (216 ± 253 ng g-1 on average), corresponding to about 5-46 mol% of their DON concentrations (15 ± 8 mol% on average). [ABSTRACT FROM AUTHOR]

Glucosides of several Fusarium mycotoxins occur in naturally infected cereals and may contribute to an increased content to the total mycotoxin load of food and feed. The paper presents the results of a fermentation procedure to produce zearalenone-4O-β-D-glucopyranoside from zearalenone using an engineered Saccharomyces cerevisiae strain, expressing the Arabidopsis thaliana UDP-glucosyltransferase UGT73C6. About 24 mg of zearalenone-4O-β-D-glucopyranoside was obtained from 50 mg of zearalenone and further purified. A total of 10 mg of the glucoside were reduced with sodium borohydride, yielding 4.1 mg α-zearalenol-4O-β-D-glucopyranoside and 4.5 mg β-zearalenol-4O-β-D-glucopyranoside at purities higher than 99%. To confirm the identities of the three produced glucosides, MS and MS/MS spectra were acquired using negative electrospray ionization. Besides the deprotonated ions at m/z 479 or 481, respectively, in full-scan mode, fragments, adducts, and dimers were recorded and assigned. MS/MS spectra of the glucosylated substances yielded the deprotonated ions of the mycotoxins zearalenone, α-zearalenol, β-zearalenol and their fragments, respectively. Unambiguous structural assignment of the three substances was achieved using two-dimensional NMR methods. This way, the glucose attachment to position C-4, the β-configuration of the sugar unit and the stereo-chemical assignment of the zearalenol hydroxyl group at C-6' were proven. [ABSTRACT FROM AUTHOR]