Characterization of (13C24) T-2 toxin and its use as an internal standard for the quantification of T-2 toxin in cereals with HPLC-MS/MS.

In this paper, the structure and the identity of fully 13C-substituted T-2 toxin were confirmed using high-resolution mass spectrometry, 1H-NMR, 13C-NMR, tandem mass spectrometry and HPLC-DAD. The purity of this compound was estimated to be at least 98.8% according to UV data. The isotopic distribution of (13C(24)) T-2 toxin indicated a total isotopic enrichment of 98.2 +/- 1.0 atom% 13C, and the application of different MS measurement modes revealed the MS/MS fragmentation pattern of T-2 toxin. Furthermore, a stable isotope dilution mass spectrometry method for the quantification of T-2 toxin was developed using (13C(24)) T-2 toxin as internal standard. The method was evaluated with and without conventional clean-up and validated for maize and oats. Both cereals showed strong matrix enhancement effects, which could be compensated for through the application of the isotope-substituted internal standard.

Characterization and application of isotope-substituted (13C15)-deoxynivalenol (DON) as an internal standard for the determination of DON.

The powerful combination of liquid chromatography and mass spectrometry (MS) is often limited by matrix effects during ionization in the MS ion source. The use of fully isotope-substituted (13C15)-deoxynivalenol ((13C15)-DON) as an internal standard (IS) corrects matrix effects and improves the accuracy of analytical methods using mass spectrometry for the quantitative determination of the Fusarium mycotoxin deoxynivalenol (DON). The IS was characterized with respect to its chromatographic purity by liquid chromatography-ultraviolet light and its isotope distribution by time-of-flight mass spectrometry. Its low-energy collision-induced dissociation behaviour was compared with DON. Moreover, this work describes the successful application of (13C15)-DON as IS for the determination of DON in maize using high-performance liquid chromatography (HPLC) electrospray (ESI) with tandem mass spectrometry. The results demonstrate that the IS can successfully correct for fluctuations during extraction and clean-up of the sample as well as the ionization of DON in the MS ion source. Random variations in ionization affect the IS in the same way as the analyte. Recoveries for DON in maize of 76% +/- 1.9% (external calibration) or 101% +/- 2.4% (internal calibration) were reached, respectively, after sample clean-up.

Fumonisin B1 - Isolation and analytical characterisation for the application as reference material.

A procedure for the production of Fumonsin B1 with a purity of more than 97% has been worked out. The isolated material was characterised by NMR and GC-MS and showed good agreement to literature data, thus proving the identity of the analysed FB1. For the purity assessment with LC-FLD and LC-MS a commercially available standard and the isolated FB1 sample were analysed under the same conditions. The overall purity of the FB1 samples was estimated as 91.9±8.1% (reference) and 97.6±2.4% (biopure), respectively.