A multi-mycotoxin stable isotope dilution LC-MS/MS method was developed for 14 Fusarium toxins including modified mycotoxins in cereals (deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, HT2-toxin, T2-toxin, enniatin B, enniatin B1, enniatin A1, enniatin A, beauvericin, fusarenone X, nivalenol, deoxynivalenol-3-glucoside, and zearalenone). The chromatographic separation of the toxins with particular focus on deoxynivalenol and deoxynivalenol-3-glucoside was achieved using a C18-hydrosphere column. An expedient sample preparation method was developed that uses solid-phase extraction for the purification of trichothecenes combined with zearalenone, enniatins, and beauvericin and provides excellent validation data. Linearity, intra-day precision, inter-day precision, and recoveries were ≥0.9982, 1-6%, 5-12%, and 79-117%, respectively. Method accuracy was verified by analyzing certified reference materials for deoxynivalenol, HT2-toxin, and T2-toxin with deviations below 7%. The results of this method found barley malt samples from 2012, 2013, and 2014 frequently contaminated with high concentrations of enniatin B, deoxynivalenol, and its modified mycotoxin deoxynivalenol-3-glucoside. Samples from 2012 were especially contaminated. Fusarenone X was not detected in any of the analyzed samples.

No abstract

Little is known about the fate of Fusarium mycotoxins during the barley malting process. To determine the fungal DNA and mycotoxin concentrations during malting, we used barley grain harvested from field plots that we had inoculated with Fusarium species that produce type A or type B trichothecenes or enniatins. Using a recently developed multimycotoxin liquid chromatography-tandem mass stable isotope dilution method, we identified Fusarium-species-specific behaviors of mycotoxins in grain and malt extracts and compared toxin concentrations to amounts of fungal DNA in the same samples. In particular, the type B trichothecenes and Fusarium culmorum DNA contents were increased dramatically up to 5400% after kilning. By contrast, the concentrations of type A trichothecenes and Fusarium sporotrichioides DNA decreased during the malting process. These data suggest that specific Fusarium species that contaminate the raw grain material might have different impacts on malt quality.

The content of tenuazonic acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively revalidated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02-100. The limit of detection (LOD) and the limit of determination (LOQ) were 0.2 µg/L and 0.6 µg/L, respectively. The mean recovery of the stable isotope dilution assay was 102 ± 3 % in the range between 1.0-100 µg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during three weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-hour urine of six volunteers from Germany (3 female, 3 male) in a concentration range of 1.3-17.3 µg/L or 2.3-10.3 ng/mg-1 creatinine, respectively. In the second study, two volunteers (1 female, 1 male) ingested 30 µg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54-81 % after six hours, depending on matrix and volunteer. After 24 hours 87-93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.