Determination of trichothecenes in wheat by capillary gas chromatography with flame ionisation detection

Trichothecenes are mycotoxins produced by several fungal genera. The Fusarium species, mainly, can contaminate a wide range of cereals used for human and animal consumption. Trichothecenes are associated with various adverse health effects in animals and humans. Deoxynivalenol (DON) and nivalenol (NIV) are the trichothecenes most commonly found worldwide, although 3-acetyldeoxynivalenol, fusarenon X, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and neosolaniol are also found. They are included in the present study. For the determination of these trichothecenes in wheat, a method based on capillary gas chromatography (GC) with flame ionisation detection (FID) has been developed and validated. The trichothecenes are extracted from the sample matrix by acetonitrile/water (84/16, v/v). Two different Mycosep® clean-up columns are used to purify the extract. The extract is evaporated to dryness and the trichothecenes are derivatised to trimethylsilyl ethers at room temperature. The residue is dissolved in iso-octane and washed with water. The final extract is analysed for trichothecenes by GC with FID. Quantification is based on the internal standard α-chloralose. The average recoveries for the trichothecenes range from 79% for NIV to 116% for DAS. The limit of quantification is 75 μg/kg for each of the individual trichothecenes. The GC-FID method produced good results in an intercomparison study of trichothecene analysis within the European Union Standards, Measurements and Testing Programme. A survey was carried out in the Netherlands in 1999 to detect the presence of trichothecenes in imported wheat. A temporary tolerance limit of 500 μg/kg is in effect in the Netherlands for DON in cleaned wheat. Seven of the 22 wheat samples exceeded this limit; one exceeded the limit by more than 100%. Thirteen of the 22 wheat samples exceeded a proposed DON tolerance limit of 120 μg/kg for cleaned wheat. Indeed, 12 samples exceeded the limit by more than 100%. Besides DON, no trichothecenes were found in the wheat samples at levels above the limit of quantification.